refactor(actions): small cleanups across models, services and routers (#39722)

Collection of small, behaviour-preserving cleanups in the Actions code.

- Fix log and error prefixes that named non-existent or wrong functions,
and wrap errors with `%w` so `errors.Is` keeps working.
- Remove unused code.
- Rely on `ctx.ServerError` / `ctx.APIErrorAuto`, which already map
`util.ErrNotExist` and friends, instead of equivalent hand-written
switches.
- Load runs referenced by commit statuses with one query instead of one
per run (used on every PR view); the result order is now stable.
- Encode an event's payload once instead of up to three times.
- Share the duplicated runner-token "get or create" logic and the
"notify and emit" call pair.
- Simplify `ToActionArtifact` / `ToActionRunner` signatures.

---------

Signed-off-by: bircni <bircni@icloud.com>
Co-authored-by: delvh <dev.lh@web.de>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/actions/jobparser/model.go

@@ -310,10 +310,6 @@ func (evt *Event) Acts() map[string][]string {
 	return evt.acts
 }
 
-func (evt *Event) Schedules() []map[string]string {
-	return evt.schedules
-}
-
 func ReadWorkflowRawConcurrency(content []byte) (*model.RawConcurrency, error) {
 	w, err := ReadWorkflow(content)
 	if err != nil {