Packaging rework (#531)

* fix: get rid of title view jank on latest beta

* Count the number of installs for each plugin (#557)

* Bump aiohttp from 3.8.4 to 3.8.5 in /backend (#558)

* fix: include Decky version in request for index.js

This avoids the If-Modified-Since logic in aiohttp and ensures Steam doesn't cache old JS,
even if the timestamps are normalized.

* fix: clean up shellcheck warnings in act runner script

* fix: gitignore settings/

* fix: ensure state directories exist when running without the installer

* feat: determine root directory correctly when running from in-tree

* fix: fix typo in CI script

* refactor: build a proper Python package with poetry

* refactor: move decky_plugin under the poetry structure

There's no need to special case it anymore, just treat it like any other Python module.

* sandboxed_plugin: better fix, attempt 2

---------

Co-authored-by: AAGaming <aagaming@riseup.net>
Co-authored-by: Party Wumpus <48649272+PartyWumpus@users.noreply.github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

backend/main.py

@@ -1,4 +1,4 @@
-# This file is needed to make the relative imports in src/ work properly.
+# This file is needed to make the relative imports in decky_loader/ work properly.
 if __name__ == "__main__":
-    from src.main import main
+    from decky_loader.main import main
     main()