feat(api): add comprehensive REST API for Project Boards

This adds a complete REST API implementation for managing repository
project boards, including projects, columns, and adding issues to columns.

API Endpoints:
- GET    /repos/{owner}/{repo}/projects          - List projects
- POST   /repos/{owner}/{repo}/projects          - Create project
- GET    /repos/{owner}/{repo}/projects/{id}     - Get project
- PATCH  /repos/{owner}/{repo}/projects/{id}     - Update project
- DELETE /repos/{owner}/{repo}/projects/{id}     - Delete project
- GET    /repos/{owner}/{repo}/projects/{id}/columns    - List columns
- POST   /repos/{owner}/{repo}/projects/{id}/columns    - Create column
- PATCH  /repos/{owner}/{repo}/projects/columns/{id}    - Update column
- DELETE /repos/{owner}/{repo}/projects/columns/{id}    - Delete column
- POST   /repos/{owner}/{repo}/projects/columns/{id}/issues - Add issue

Features:
- Full Swagger/OpenAPI documentation
- Proper permission checks
- Pagination support for list endpoints
- State filtering (open/closed/all)
- Comprehensive error handling
- Token-based authentication with scope validation
- Archive repository protection

New Files:
- modules/structs/project.go: API data structures
- routers/api/v1/repo/project.go: API handlers
- routers/api/v1/swagger/project.go: Swagger responses
- services/convert/project.go: Model converters
- tests/integration/api_repo_project_test.go: Integration tests

Modified Files:
- models/project/issue.go: Added AddOrUpdateIssueToColumn function
- routers/api/v1/api.go: Registered project API routes
- routers/api/v1/swagger/options.go: Added project option types
- templates/swagger/v1_json.tmpl: Regenerated swagger spec

fix(api): remove duplicated permission checks in project handlers

Route middleware reqRepoReader(unit.TypeProjects) wraps the entire
/projects route group, and reqRepoWriter(unit.TypeProjects) is applied
to each mutating route individually in api.go. These middleware run
before any handler fires and already gate access correctly.

The inline CanRead/CanWrite checks at the top of all 10 handlers were
therefore unreachable dead code — removed from ListProjects, GetProject,
CreateProject, EditProject, DeleteProject, ListProjectColumns,
CreateProjectColumn, EditProjectColumn, DeleteProjectColumn, and
AddIssueToProjectColumn.

The now-unused "code.gitea.io/gitea/models/unit" import is also removed.

Addresses review feedback on: https://github.com/go-gitea/gitea/pull/36008

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

fix(api): replace AddOrUpdateIssueToColumn with IssueAssignOrRemoveProject

The custom AddOrUpdateIssueToColumn function introduced by this PR was
missing three things that the existing IssueAssignOrRemoveProject provides:

1. db.WithTx transaction wrapper — raw DB updates without a transaction
   can leave the database in a partial state on error.

2. CreateComment(CommentTypeProject) — assigning an issue to a project
   column via the UI creates a comment on the issue timeline. The API
   doing the same action silently was an inconsistency.

3. CanBeAccessedByOwnerRepo ownership check — IssueAssignOrRemoveProject
   validates that the issue is accessible within the repo/org context
   before mutating state.

AddOrUpdateIssueToColumn is removed entirely. AddIssueToProjectColumn
now delegates to issues_model.IssueAssignOrRemoveProject, which already
has the issue object loaded earlier in the handler.

Addresses review feedback on: https://github.com/go-gitea/gitea/pull/36008

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

fix(api): remove unnecessary pagination from ListProjectColumns

Project columns are few in number by design (typically 3-8 per board).
The previous implementation fetched all columns from the DB then sliced
the result in memory — adding complexity and a misleading Link header
without any practical benefit.

ListProjectColumns now returns all columns directly. The page/limit
query parameters and associated swagger docs are removed.

Addresses review feedback on: https://github.com/go-gitea/gitea/pull/36008

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

fix(api): regenerate swagger spec after removing ListProjectColumns pagination

Removes the page and limit parameters from the generated swagger spec
for the ListProjectColumns endpoint, matching the handler change that
dropped in-memory pagination.

Co-authored-by: Claude <noreply@anthropic.com>

test(api): remove pagination assertion from TestAPIListProjectColumns

ListProjectColumns no longer supports pagination — it returns all columns
directly. Remove the page/limit test case that expected 2 of 3 columns.

Co-authored-by: Claude <noreply@anthropic.com>

fix(api): implement proper pagination for ListProjectColumns

Per contribution guidelines, list endpoints must support page/limit
query params and set X-Total-Count header.

- Add CountColumns and GetColumnsPaginated to project model (DB-level,
  not in-memory slicing)
- ListProjectColumns uses utils.GetListOptions, calls paginated model
  functions, and sets X-Total-Count via ctx.SetTotalCountHeader
- Restore page/limit swagger doc params on the endpoint
- Regenerate swagger spec
- Integration test covers: full list with X-Total-Count, page 1 of 2,
  page 2 of 2, and 404 for non-existent project

Co-authored-by: Claude <noreply@anthropic.com>

modules/structs/project.go

@@ -1,4 +1,4 @@
-// Copyright 2026 The Gitea Authors. All rights reserved.
+// Copyright 2025 The Gitea Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
 package structs
@@ -10,24 +10,83 @@ import (
 // Project represents a project
 // swagger:model
 type Project struct {
-	// ID is the unique identifier for the project
-	ID int64 `json:"id"`
-	// Title is the title of the project
-	Title string `json:"title"`
-	// Description provides details about the project
-	Description string `json:"description"`
-	// OwnerID is the owner of the project (for org-level projects)
-	OwnerID int64 `json:"owner_id,omitempty"`
-	// RepoID is the repository this project belongs to (for repo-level projects)
-	RepoID int64 `json:"repo_id,omitempty"`
-	// CreatorID is the user who created the project
-	CreatorID int64 `json:"creator_id"`
-	// IsClosed indicates if the project is closed
-	IsClosed bool `json:"is_closed"`
+	ID              int64      `json:"id"`
+	Title           string     `json:"title"`
+	Description     string     `json:"description"`
+	OwnerID         int64      `json:"owner_id,omitempty"`
+	RepoID          int64      `json:"repo_id,omitempty"`
+	CreatorID       int64      `json:"creator_id"`
+	IsClosed        bool       `json:"is_closed"`
+	TemplateType    int        `json:"template_type"`
+	CardType        int        `json:"card_type"`
+	Type            int        `json:"type"`
+	NumOpenIssues   int64      `json:"num_open_issues,omitempty"`
+	NumClosedIssues int64      `json:"num_closed_issues,omitempty"`
+	NumIssues       int64      `json:"num_issues,omitempty"`
 	// swagger:strfmt date-time
-	Created time.Time `json:"created_at"`
+	Created    time.Time  `json:"created"`
 	// swagger:strfmt date-time
-	Updated time.Time `json:"updated_at"`
+	Updated    time.Time  `json:"updated"`
 	// swagger:strfmt date-time
-	Closed *time.Time `json:"closed_at,omitempty"`
+	ClosedDate *time.Time `json:"closed_date,omitempty"`
+	URL        string     `json:"url,omitempty"`
 }
+
+// CreateProjectOption represents options for creating a project
+// swagger:model
+type CreateProjectOption struct {
+	// required: true
+	Title        string `json:"title" binding:"Required"`
+	Description  string `json:"description"`
+	TemplateType int    `json:"template_type"`
+	CardType     int    `json:"card_type"`
+}
+
+// EditProjectOption represents options for editing a project
+// swagger:model
+type EditProjectOption struct {
+	Title       *string `json:"title,omitempty"`
+	Description *string `json:"description,omitempty"`
+	CardType    *int    `json:"card_type,omitempty"`
+	IsClosed    *bool   `json:"is_closed,omitempty"`
+}
+
+// ProjectColumn represents a project column (board)
+// swagger:model
+type ProjectColumn struct {
+	ID        int64     `json:"id"`
+	Title     string    `json:"title"`
+	Default   bool      `json:"default"`
+	Sorting   int       `json:"sorting"`
+	Color     string    `json:"color,omitempty"`
+	ProjectID int64     `json:"project_id"`
+	CreatorID int64     `json:"creator_id"`
+	NumIssues int64     `json:"num_issues,omitempty"`
+	// swagger:strfmt date-time
+	Created   time.Time `json:"created"`
+	// swagger:strfmt date-time
+	Updated   time.Time `json:"updated"`
+}
+
+// CreateProjectColumnOption represents options for creating a project column
+// swagger:model
+type CreateProjectColumnOption struct {
+	// required: true
+	Title string `json:"title" binding:"Required"`
+	Color string `json:"color,omitempty"`
+}
+
+// EditProjectColumnOption represents options for editing a project column
+// swagger:model
+type EditProjectColumnOption struct {
+	Title   *string `json:"title,omitempty"`
+	Color   *string `json:"color,omitempty"`
+	Sorting *int    `json:"sorting,omitempty"`
+}
+
+// AddIssueToProjectColumnOption represents options for adding issues to a project
+// swagger:model
+type AddIssueToProjectColumnOption struct {
+	// required: true
+	IssueIDs []int64 `json:"issue_ids" binding:"Required"`
+}