feat(code): add .worktreeinclude support

[adboio]

Problem

tragically, i think we really should make worktrees work well

Changes

less tragically, i think this small change makes it all better :)

• added support for .worktreeinclude and .worktreelink files
• they do what they sound like; include copies files and link symlinks files
• both are filtered to only include files that are gitignored, which matches cc's implementation

How did you test this?

added these tiny pieces to the main repo, and it all works pretty smoothly: https://app.graphite.com/github/pr/PostHog/posthog/52566

[adboio]

• feat(code): add .worktreeinclude support #1344 👈 (View in Graphite)
• main

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[jonathanlab]

nice, lgtm! wonder if we could do with some docs about this as well

[jonathanlab]

nit: I assume this is to circumvent the husky hooks in the posthog/posthog repository right? Do we want to make it configurable if these hooks are enabled/disabled? Totally up to you

[adboio]

yes, but not to circumvent, just to delay

we still run these later -- we just skip them here so the worktreeinclude and worktreelink processes can complete first, as the hooks may depend on them (ours do)

[jonathanlab]

Also would be awesome if we could let users config this in the Worktree settings page, but thats for another PR :D

[adboio]

@jonathanlab agree! if this works out, i'll take another pass to imrpove the UX a bit:

• add config stuff as you suggest
• probably improve on the loading states / transitions
• maybe have the post-checkout hooks run in parallel with the session init just as a wall-clock time saver