fix(procrastinate): skip built-in tasks; document known limitations

- ProcrastinateSystemIntegration.track_task now refuses task names
  starting with "builtin:" or "procrastinate." so Procrastinate's own
  housekeeping jobs aren't auto-tracked.
- README documents three known limitations: configure().defer(),
  batch_defer*, and post-init add_tasks_from.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: snopoke

README.md

@@ -92,3 +92,9 @@ taskbadger.init(
     )],
 )
 ```
+
+#### Known limitations
+
+- **`task.configure(...).defer(...)` is not tracked.** Procrastinate's `configure()` returns a separate `JobDeferrer` whose methods bypass our wrapper. Use `task.defer(...)` directly for tracked deferrals. Tasks deferred via `configure().defer()` will run normally but will not appear in TaskBadger.
+- **`task.batch_defer*` is not tracked.** Same reason as `configure().defer()`.
+- **Tasks added via `app.add_tasks_from(blueprint)` after `ProcrastinateSystemIntegration` is constructed are not auto-instrumented.** Construct the integration after all blueprints are registered, or apply `@track` to those tasks explicitly.

taskbadger/systems/procrastinate.py

@@ -46,6 +46,11 @@ def track_task(self, task_name):
         if not self.auto_track_tasks:
             return False
 
+        # Never auto-track Procrastinate's built-in housekeeping tasks
+        # (e.g. ``builtin:procrastinate.builtin_tasks.remove_old_jobs``).
+        if task_name.startswith("builtin:") or task_name.startswith("procrastinate."):
+            return False
+
         if self.excludes:
             for exclude in self.excludes:
                 if re.fullmatch(exclude, task_name):