fix(actions): correctness and hardening fixes (#38518)

Various fixes to actions

1. **Cap total jobs per run in reusable-workflow expansion** — only
nesting depth was capped, so fan-out + nested reusable workflows could
explode job-row inserts and exhaust the DB from a single push. Now
enforces `MaxJobNumPerRun` in the insert path.
2. **Reject rerun-failed when a run has no failed jobs** — an empty job
list meant "re-run everything", so `rerun-failed` on a green run re-ran
all jobs. Now errors (web + API).
3. **Don't adopt external commit statuses into the legacy hash** — the
pre-#35699 Context-only hash matched API-posted statuses too, collapsing
two same-named workflows into one check. Now limited to Actions-user
rows.
4. **Don't cut post-cancel cleanup short in `StopEndlessTasks`** — the
sweep force-stopped just-cancelled jobs mid-cleanup. Now targets
`StatusRunning` only; stalled cancels stay covered by `StopZombieTasks`.
5. **Avoid redundant run reload in `GenerateGiteaContext`** — resolving
`github.triggering_actor` reloaded the run already passed in. Now loads
only the trigger user via new `ActionRunAttempt.LoadTriggerUser`.

---------

Co-authored-by: Zettat123 <zettat123@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

models/actions/run_attempt.go

@@ -62,14 +62,16 @@ func (attempt *ActionRunAttempt) LoadAttributes(ctx context.Context) (err error)
 		attempt.Run = run
 	}
 
-	if attempt.TriggerUser == nil {
-		attempt.TriggerUserID, attempt.TriggerUser, err = user_model.GetPossibleUserByID(ctx, attempt.TriggerUserID)
-		if err != nil {
-			return err
-		}
-	}
+	return attempt.LoadTriggerUser(ctx)
+}
 
-	return nil
+// LoadTriggerUser loads the attempt's trigger user if not already loaded.
+func (attempt *ActionRunAttempt) LoadTriggerUser(ctx context.Context) (err error) {
+	if attempt.TriggerUser != nil {
+		return nil
+	}
+	attempt.TriggerUserID, attempt.TriggerUser, err = user_model.GetPossibleUserByID(ctx, attempt.TriggerUserID)
+	return err
 }
 
 func GetRunAttemptByRepoAndID(ctx context.Context, repoID, attemptID int64) (*ActionRunAttempt, error) {

models/actions/run_job_list.go

@@ -159,3 +159,12 @@ func (opts FindRunJobOptions) ToOrders() string {
 }
 
 var _ db.FindOptionsOrder = FindRunJobOptions{}
+
+// CountRunJobsByRunAndAttemptID counts the jobs belonging to the given run attempt.
+// It is used to enforce MaxJobNumPerRun when reusable-workflow expansion inserts new jobs.
+func CountRunJobsByRunAndAttemptID(ctx context.Context, runID, runAttemptID int64) (int64, error) {
+	return db.Count[ActionRunJob](ctx, FindRunJobOptions{
+		RunID:        runID,
+		RunAttemptID: optional.Some(runAttemptID),
+	})
+}