feat(tapo-agent): add schedule/countdown timer API support

- Fork tapo crate to add missing schedule/timer APIs
- Add get_countdown_rules, get_schedule_rules, get_next_event methods
- New readings: countdown_active, countdown_remain, schedule_count,
  schedule_active_count, next_event_time
- Add local compilation to build script alongside cross-compilation
- Implement offline polling - device collection continues when server disconnects
- Add more device readings: on_time, signal_level, rssi, runtime_today/month, energy_month

Vendored tapo fork in tapo-fork/ with minimal changes to add schedule APIs.

agents/tapo/tapo-fork/CONTRIBUTING.md

@@ -0,0 +1,28 @@
+# Contributing
+
+Contributions are welcome and encouraged! See [/issues][issues] for ideas, or suggest your own!
+If you're thinking to create a PR with large feature/change, please first discuss it in an issue.
+
+[issues]: https://github.com/mihai-dinculescu/tapo/issues
+
+## Releasing new versions
+
+- Update version in `tapo/Cargo.toml`
+- Update version in `tapo-py/pyproject.toml` (two places)
+- Update CHANGELOG.md
+- Commit
+- Add tag
+
+  ```bash
+  git tag -a vX.X.X -m "vX.X.X"
+  ```
+
+- Push
+
+  ```bash
+  git push --follow-tags
+  ```
+
+- Create the [release][release].
+
+[releases]: https://github.com/mihai-dinculescu/tapo/releases