Add "optimize alternative icons" insight handling

[NicoHinderling]

Closes EME-50

I tried to match the emerge implementation as much as possible. There's a ~6% size difference between the ultimately optimized icons compared to what's produced by the emerge code But it is consistent across all the images and appears to be related to the fact that we are using a different HEIC encoder:

• in emerge we use Apple's native HEIC encoding via swift (Core Graphics/ImageIO)
• in launchpad we use libheif

I tried reducing the image quality from 85% to 75% to get the size reduction closer to emerge's but it didn't reduce the size enough to justify an extra 10% loss in quality

[linear]

EME-50 Optimize icons

[codecov]

Codecov Report

❌ Patch coverage is 89.52381% with 22 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.96%. Comparing base (7683d66) to head (9236935).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...aunchpad/size/insights/apple/image_optimization.py	75.60%	9 Missing and 1 partial ⚠️
src/launchpad/artifacts/apple/zipped_xcarchive.py	56.25%	4 Missing and 3 partials ⚠️
...ize/insights/apple/alternate_icons_optimization.py	92.85%	2 Missing and 1 partial ⚠️
tests/unit/test_alternate_icons_optimization.py	98.11%	0 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #417      +/-   ##
==========================================
+ Coverage   79.77%   79.96%   +0.18%     
==========================================
  Files         147      149       +2     
  Lines       11850    12027     +177     
  Branches     1208     1223      +15     
==========================================
+ Hits         9453     9617     +164     
- Misses       1962     1969       +7     
- Partials      435      441       +6     

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[trevor-e]

ai generated comment? lol

[NicoHinderling]

woops

[trevor-e]

Use logger.exception, it will automatically capture the exception details. Also avoid using string interpolation in the message so it doesn't create separate issues for us each time.

[trevor-e]

Same, logger.exception()

[trevor-e]

Can these two methods be combined into something like _find_images() -> List[FileInfo]? The de-duping can be merged into that as well. The current structure here is a bit awkward IMO, the iterator just converts it to a list anyways. It looks like the subclasses are responsible for returning a list of images that should be considered for processing.

[trevor-e]

Similarly, the _analyze_image_optimization override doesn't fit in nicely here since we lose the ThreadPoolExecutor logic and duplicate a lot of size-checking code. Maybe there could be some kind of overridable "preprocess" or "transform" method that gets called before _analyze_image_optimization so that method doesn't have to be overriden?