feat(FN-1524): add POST /routines/:id/trigger endpoint

- Add POST /routines/:id/trigger as canonical endpoint for manual routine triggers
- Keep POST /routines/:id/run as backward-compatible alias with identical behavior
- Remove duplicate recordRun calls from routine route handlers (persistence handled by RoutineRunner.completeRoutineExecution)
- Update webhook auth to return 401 instead of 403 for missing/invalid signature headers
- Add comprehensive tests for /trigger endpoint and double-persist fix

packages/dashboard/app/api.ts

@@ -1783,7 +1783,7 @@ export async function deleteRoutine(id: string): Promise<void> {
 }
 
 export function runRoutine(id: string): Promise<RoutineRunResponse> {
-  return api<RoutineRunResponse>(`/routines/${id}/run`, {
+  return api<RoutineRunResponse>(`/routines/${id}/trigger`, {
     method: "POST",
   });
 }