feat: support icon color - followup

[brisvag]

Trying to pick up #130!

I fixed conflicts and brought it up to date. @tlambert03 was there something specific with that PR that was incomplete or you wanted to finish?

[codecov]

Codecov Report

❌ Patch coverage is 84.78261% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 99.27%. Comparing base (7f1e493) to head (17b44e0).

Files with missing lines	Patch %	Lines
src/app_model/types/_icon.py	66.66%	4 Missing ⚠️
src/app_model/_app.py	66.66%	3 Missing ⚠️

❌ Your patch check has failed because the patch coverage (84.78%) is below the target coverage (100.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #277      +/-   ##
==========================================
- Coverage   99.62%   99.27%   -0.36%     
==========================================
  Files          31       31              
  Lines        1878     1918      +40     
==========================================
+ Hits         1871     1904      +33     
- Misses          7       14       +7     

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[tlambert03]

@brisvag, I think the main reason that PR stalled is because of the problem with theme changes. as mentioned in the first comment:

note that svg-colored icons don't currently change if the parent style sheet changes. This is just a generally harder thing to solve (and one of the few benefits of font-icons). However, we could, as magicgui does, attach QPallete change events here and auto-change icon colors in a future PR.

so, currently here:

  app = Application("myapp")
  app.theme_mode = "dark"  # or let it auto-detect

  Action(
      id="my.action",
      title="Do Thing",
      icon={"dark": "mdi:some-icon", "color_dark": "#FFFFFF", "color_light": "#000000"},
      ...
  )

The icon color is resolved once — at the moment the QAction or QMenuSubMenu is constructed. The resulting QIcon is a static pixmap/SVG baked with whatever color was chosen at creation time. If the user later, changes app.theme_mode from "dark" to "light", or wwitches their OS/Qt theme (causing the QPalette to change), nothing re-runs to_qicon(). The icons stay the old color. There's no signal, no QPalette change event listener, no theme_mode change signal — nothing triggers a re-render.

so, it feels like a partially implemented thing that will pretty quickly have a bug report or feature request