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>

.gitignore

@@ -29,7 +29,7 @@ MANIFEST
 #  Usually these files are written by a python script from a template
 #  before PyInstaller builds the exe, so as to inject date/other infos into it.
 *.manifest
-*.spec
+backend/dist/
 
 # Installer logs
 pip-log.txt
@@ -163,3 +163,4 @@ plugins/*
 act/.directory
 act/artifacts/*
 bin/act
+settings/