refactor(ruff): enable ruff preview rules (#2120)

[cfxegbert]

Branch summary: refactor/2120-enable-preview-ruff-rules

1 commit ahead of main: d16f4b39 refactor(ruff): enable ruff preview rules (#2120)

34 files changed, +51 / −62 lines.

Main change

Enables Ruff’s preview rules in ruff.toml:

[lint]
preview = true

The rest of the diff is code updated to satisfy those stricter checks.

Fix categories

Category	Examples
Spacing in type annotations	flags: int=0 → flags: int = 0 across many rezgui widgets, models, and windows — including ContextSubWindow.py
Comment formatting	#print → # print, #self → # self, #no_color → # no_color
Section dividers	#=== → # === in rex.py, memory.py
Unused imports	Removed redundant import os where only os.path is used (util.py, backcompat.py, build plugins, shell plugins, bundle.py)
Dead commented code	Removed old process-tracker stubs in App.py, ContextToolsWidget.py; cleaned inline comments in ToolWidget calls
Other style	### → # ## in _entry_points.py; blank line after imports in ChangelogEdit.py; indentation fix in VariantCellWidget.py; joined split string in platform_.py

I used some help from an LLM to create the summary for this PR

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 61.30%. Comparing base (9c1cdee) to head (c0f6eae).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2140      +/-   ##
==========================================
- Coverage   61.31%   61.30%   -0.02%     
==========================================
  Files         164      164              
  Lines       20568    20561       -7     
  Branches     3575     3575              
==========================================
- Hits        12611    12604       -7     
  Misses       7085     7085              
  Partials      872      872              

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