feat: Add worker --reload option

[eelkevdbos]

Context
In contrast to the web server, these is no option for the worker to reload on code changes. Incorporating this would speed up development and prevent a lot of manual rebooting the plain dev command.

Current workaround
Watchdog to facilitate this, but it feels like the frameworks setup would be to provide it 'batteries included'.

[tool.plain.dev.run]
worker = {cmd = "uv run watchmedo auto-restart --patterns='*.py' --recursive uv run plain worker run"}

Proposed solution
Having a --reload option for the worker run command that does the reloading for us (e.g. plain worker run --reload). Maybe even let it be the default if going for convention over configuration.

[davegaeddert]

(I'm going to try moving these to discussions so I can leave them open without cluttering issues...)

I will try to do more documentation on the worker soon — kudos for figuring some of this out on your own! I do something similar myself and just documented that here:

[tool.plain.dev.run]
worker = {cmd = "plain models db-wait && watchfiles --filter python \"plain worker run --stats-every 0 --max-processes 2\" ."}
worker-slow = {cmd = "plain models db-wait && watchfiles --filter python \"plain worker run --queue slow --stats-every 0 --max-processes 2\" ."}

I agree that from a "batteries included" approach it could be nice to build this in. On the web server itself, we're just relying on the gunicorn feature for reloading so I haven't actually had to decide if or how to handle this yet (or what dependency to trust, etc). I'm going to leave it as a documentation solution for now but will definitely keep this in mind — for both this and #25 it would obviously be much nicer to do plain worker run --reload or plain worker run --dev or something than making everyone write the whole mess above.

[davegaeddert]

Update: the plain models db-wait part is no longer necessary with the new version of plain.dev. The watchfiles part is still required though if you want the worker to autoreload.