feat: add default app and manifest watch config

[zimeg]

Summary

This PR adds a default app and manifest option to file watching for server restarts and app reinstalls.

Following: slackapi/slack-cli#310

Testing

Build these changes with the CLI changes noted above. Then reinstall and reload an app:

$ slack run          # Run an app and keep it running
$ vim manifest.json  # Update the manifest file
$ vim app.py         # Update the app configuration
$ vim listeners/__init__.py  # Confirm nested directories work too

⚠️ Note: The manifest.source of ".slack/config.json" must be local for this to work with manifest changes!

Special notes

CLI version >=3.12.0 is required for these changes to be used in development, but these will be released in order or together if all goes well in review 👾

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.
• I've run ./scripts/install_and_run_tests.sh after making the changes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.68%. Comparing base (7d9a5cf) to head (d3b5cb8).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #89   +/-   ##
=======================================
  Coverage   94.68%   94.68%           
=======================================
  Files          11       11           
  Lines         207      207           
=======================================
  Hits          196      196           
  Misses         11       11           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[WilliamBergamin]

Tested this out locally 🚀 The experience is much better then I expected 🌟

My only concern before merging this is that the CLI seems to be using a keyboard interrupt to stop the process and this is leading to a traceback being printed 🤔 I don't think this traceback should be printed when the CLI does its "refresh"

INFO:slack_bolt.App:Starting to receive messages from a new connection (session id: c946512435)
App change detected: ~/bolt-python-search-template/listeners/functions/search.py, restarting server...
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "~/bolt-python-search-template/.venv/lib/python3.13/site-packages/slack_cli_hooks/hooks/start.py", line 44, in <module>
    start(os.getcwd())
    ~~~~~^^^^^^^^^^^^^
  File "~/bolt-python-search-template/.venv/lib/python3.13/site-packages/slack_cli_hooks/hooks/start.py", line 37, in start
    runpy.run_path(entrypoint_path, run_name="__main__")
    ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen runpy>", line 287, in run_path
  File "<frozen runpy>", line 98, in _run_module_code
  File "<frozen runpy>", line 88, in _run_code
  File "~/bolt-python-search-template/app.py", line 19, in <module>
    SocketModeHandler(app, os.environ.get("SLACK_APP_TOKEN")).start()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "~/bolt-python-search-template/.venv/lib/python3.13/site-packages/slack_bolt/adapter/socket_mode/base_handler.py", line 58, in start
    Event().wait()
    ~~~~~~~~~~~~^^
  File "/Users/wbergamin/.pyenv/versions/3.13.1/lib/python3.13/threading.py", line 659, in wait
    signaled = self._cond.wait(timeout)
  File "/Users/wbergamin/.pyenv/versions/3.13.1/lib/python3.13/threading.py", line 359, in wait
    waiter.acquire()
    ~~~~~~~~~~~~~~^^
KeyboardInterrupt

Not sure if this is something we could handle on the CLI side 🤔 from my quick search it seems like sending a syscall.SIGTERM to the python process might prevent this tracback log from showing up

[zimeg]

@WilliamBergamin Thanks a ton for taking this for a spin! 🚲 ✨

IIRC Windows doesn't support the same syscall signals that Unix setups often do. We use the most general interrupt between processes to avoid these platform nuances in CLI code:

https://github.com/slackapi/slack-cli/blob/66766a97e90046d9db7d5697d338d3ccea433c52/internal/pkg/platform/localserver.go#L259

The SIGILL and SIGTERM signals aren't generated under Windows.

🔗 https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/signal?view=msvc-170

I agree we might find improvements to these outputs - perhaps clearing the screen between restarts is useful - but for now this output might be alright toward iterations in app development?