Fix rounded macOS icon on older Macs (#8018)

Older macOS versions display Buzz’s opaque icon as an oversized square.
Bake rounded corners and transparent padding into the macOS `.icns`,
preserving the original bee artwork and leaving other platforms
unchanged.

Generation uses Hermit-pinned uv, Python 3.14.3, and Pillow 12.2.0.
`scripts/macos-icon.sh --check` regenerates temporarily and compares all
decoded representations; macOS CI runs it before packaging. Pixel
reproducibility is verified independently of Apple’s ICNS container
encoding.

Validated native AppKit preview, all 10 representations, fresh-cache
generation, one-pixel/missing-representation drift rejection, workflow
lint, and pre-push checks. Full local `just ci` is running. Packaged
Dock checks on older/current macOS remain outstanding.

---------

Signed-off-by: kenny lopez <klopez4212@gmail.com>

.github/workflows/_ci-desktop-macos.yml

@@ -31,6 +31,8 @@ jobs:
     steps:
       - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
       - uses: cashapp/activate-hermit@cea9af7913204a965fd488637a8d1811bba2e616 # v1
+      - name: Verify macOS icon representations
+        run: scripts/macos-icon.sh --check
       - uses: Swatinem/rust-cache@e18b497796c12c097a38f9edb9d0641fb99eee32
         with:
           workspaces: desktop/src-tauri

.github/workflows/ci.yml

@@ -66,6 +66,10 @@ jobs:
               - 'scripts/normative-corpus.json'
               - 'justfile'
             desktop:
+              - 'scripts/generate-macos-icon.py'
+              - 'scripts/macos-icon.sh'
+              - 'bin/uv'
+              - 'bin/.uv-*.pkg'
               - 'scripts/model-capabilities.json'
               - 'scripts/normative-corpus.json'
               - 'desktop/**'