Add YouTube as a platform

[serrebidev]

Hi! First off — I love FastSM. It's become my daily driver, and I really appreciate the work you put into it.

Since YouTube keeps drifting more and more toward being a social network (subscriptions, community posts, comments, likes), I thought I'd take a shot at adding it as a platform alongside Mastodon and Bluesky. Totally understand if it's not a direction you want to take the app — no hard feelings if you'd rather not merge it.

What this adds

• OAuth 2.0 login using Google's installed-app (loopback) flow — browser consent once, then a long-lived refresh token is persisted and silently refreshed.
• YouTube Data API v3: account identity, subscriptions, likes/ratings, subscribe/unsubscribe, comments.
• InnerTube for search and the recommendations/home feed (the parts the official API doesn't expose).
• A per-account Templates tab with a $description$ placeholder so YouTube posts render the way you want (default shows title + author; description is opt-in).
• Platform-select wiring (radio button in the add-account dialog) and PyInstaller build support for the lazy-imported Google libraries.

Credentials / security

No secrets are committed. The OAuth client secret lives in platforms/youtube/client_secret.json, which is git-ignored. The bundled client constants in oauth.py are intentionally left empty for you to fill in with a verified FastSM Google client (or users can supply their own via prefs / a local client_secret.json). The one hardcoded key in innertube.py is the public InnerTube key the YouTube web player ships to everyone, not a personal credential.

Testing

I tested this end-to-end with a testing key (my own Google Cloud OAuth client) and it works — login, loading the account, subscriptions, search, and posting templates all function.

Happy to adjust anything or split it up if that's easier to review. Thanks for considering it!

[serrebidev]

Follow-up: I vendored the search backend so this doesn't depend on the unmaintained youtube-search-python on PyPI.

• The maintained fork now lives at platforms/youtube/vendor/youtubesearchpython/ (26 source files, MIT — upstream LICENSE included, plus a vendor/README.md with attribution and the reason it's vendored: updated InnerTube clientVersion/renderer paths so search keeps working).
• It's made importable as the top-level youtubesearchpython via a small sys.path shim in platforms/youtube/__init__.py, so the existing import youtubesearchpython calls work unchanged with no PyPI install.
• requirements.txt drops the old pin and adds the library's one real runtime dep, httpx.
• build.py bundles the vendor tree (--add-data + --collect-all httpx) and adds the hidden imports PyInstaller can't trace through the runtime shim.

I verified the import resolves to the vendored copy (v1.6.2) and loads cleanly. Happy to drop the vendoring and go back to a plain PyPI dependency instead if you'd prefer that — whatever's easier for you to maintain.