fix(ci): remove deprecated darwin-x64 build from release workflow

The macOS-13 runner has been retired by GitHub Actions, causing the
darwin-x64 build to be cancelled. This blocked the installer build
because build-windows-installer depends on ALL matrix jobs completing.

Changes:
- Remove darwin-x64 (macOS-13) from build matrix
- Remove darwin-x64 from release artifacts and documentation
- Keep linux-x64, darwin-arm64 (Apple Silicon), and windows-x64

Impact:
- macOS Intel users will no longer have pre-built binaries
- darwin-arm64 binaries may work on Intel Macs via Rosetta 2
- Installer builds will no longer be blocked by cancelled jobs

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: Test

.github/workflows/release-mcpb.yml

@@ -18,8 +18,6 @@ jobs:
         include:
           - os: ubuntu-22.04
             platform: linux-x64
-          - os: macos-13  # Intel Mac
-            platform: darwin-x64
           - os: macos-latest  # Apple Silicon Mac (M1/M2)
             platform: darwin-arm64
           - os: windows-latest
@@ -664,7 +662,6 @@ jobs:
           ## Platforms
 
           - **Windows Installer**: mcpb-windows-x64-setup.exe (automated setup with GUI)
-          - **macOS (Intel)**: mcpb-darwin-x64.zip
           - **macOS (Apple Silicon)**: mcpb-darwin-arm64.zip
           - **Linux (x86_64)**: mcpb-linux-x64.zip
           - **Windows (Manual)**: mcpb-windows-x64.zip
@@ -683,7 +680,6 @@ jobs:
           draft: false
           prerelease: false
           files: |
-            artifacts/mcpb-darwin-x64/mcpb-darwin-x64.mcpb
             artifacts/mcpb-darwin-arm64/mcpb-darwin-arm64.mcpb
             artifacts/mcpb-linux-x64/mcpb-linux-x64.mcpb
             artifacts/mcpb-windows-x64/mcpb-windows-x64.mcpb