fix: Fixed logic error in index_tweak_folder which resulted in parsing all tweaks twice

[jamakoiv]

Description

The implementation of rejecting same tweaks in index_tweak_folder only considered duplicates inside the same folder,
not possible duplicates from other previously indexed folders. Since the tweak layer and name are constructed from the folder structure and filename, and no known OS filesystem allows two identical filenames in same folder, this resulted in dead code.
The rejection of duplicates only happened after the files had been already read and parsed, which created double the amount of calls to the JSON-parser which is quite slow in python.

Fixes:

• Rewrote the index_tweak_folder to use Path.rglob -function for getting tweak filenames. rglob handles subdirectories without need for recursive function pattern.
• Duplicate tweaks are dropped based on the tweak name before parsing. The tweaks found in DIR_USER are prioritized over the ones in SYSTEM and PACKAGE.
• Refactored reading and parsing the tweak files to separate parse_tweak -function. This makes it easier to use multiprocessing to parse the tweaks if necessary in the future.
• get_tweak -function now parses only the requested tweak instead of parsing all tweaks and returning just the requested one.
• Added basic unit-tests. The test tweak-files screw up the line-counts, so i can separate these to another pull-request if you prefer cleaner history.

With the above changes cProfile.run("get_tweaks()") went from

7298618 function calls (6548291 primitive calls) in 2.461 seconds

to

3628019 function calls (3256901 primitive calls) in 1.244 seconds

and cProfile.run("get_tweak('themes.reset')") from

7298619 function calls (6548292 primitive calls) in 2.417 seconds

to

116207 function calls (105288 primitive calls) in 0.048 seconds

API-changes:

• index_tweak_folder return value changed from dict[str, TweakData] to dict[str, Path]. Only called internally in tweaks.py.
• get_tweak_names return value changed from set[str] to dict[str, Path]. All code calling get_tweak_names is ok with this.

Type of Change

• feat: New feature
• fix: Bug fix
• docs: Documentation update
• tweak: New tweak file
• test: Test additions/changes
• chore: Build/tooling changes

Checklist

• PR title follows Conventional Commits format
• Code follows project style (type hints, dataclasses)
• Added tests for new functionality (if applicable)
• Read CONTRIBUTING.md

[wojtmic]

Thanks for the fix!