ci: disable Windows ARM64 (Bun lacks stable ARM64 binaries)

The oven-sh/setup-bun action fails with 404 when trying to download
Bun for Windows ARM64. Re-enable when Bun adds proper support.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: ochafik

.github/workflows/ci.yml

@@ -18,8 +18,9 @@ jobs:
             name: Linux ARM64
           - os: windows-latest
             name: Windows x64
-          - os: windows-11-arm
-            name: Windows ARM64
+          # Windows ARM64 disabled: Bun doesn't have stable ARM64 binaries yet (setup-bun fails with 404)
+          # - os: windows-11-arm
+          #   name: Windows ARM64
           - os: macos-latest
             name: macOS ARM64
           - os: macos-13
@@ -74,8 +75,9 @@ jobs:
             name: Linux ARM64
           - os: windows-latest
             name: Windows x64
-          - os: windows-11-arm
-            name: Windows ARM64
+          # Windows ARM64 disabled: Bun doesn't have stable ARM64 binaries yet (setup-bun fails with 404)
+          # - os: windows-11-arm
+          #   name: Windows ARM64
           - os: macos-latest
             name: macOS ARM64