feat: add libc tagging support for Linux packages

Implement --tag-libc support for prebuildify to distinguish between
glibc and musl variants on Linux, following official N-API best
practices for precompiled binary distribution.

Changes:
- Add --tag-libc flag to prebuildify wrapper (ci-workflow.ts)
- Update platform package naming to include libc suffix (platform-package.ts)
- Update CI workflow to pass --libc glibc for Linux builds (ci.yml)
- Update runtime binding loader to resolve glibc-tagged packages (binding.ts)
- Update package.json optionalDependencies with new package name
- Update create-platform-packages script for glibc platform config
- Add comprehensive build system documentation (build-system.md)
- Add detailed implementation guide (libc-tagging-implementation.md)

Package name change:
- Before: @pproenca/node-webcodecs-linux-x64
- After: @pproenca/node-webcodecs-linux-x64-glibc

This change improves platform targeting and aligns with official
prebuildify guidance for libc tagging. Infrastructure is now ready
for future musl (Alpine Linux) support.

Ref: https://nodejs.org/api/n-api.html#uploading-precompiled-binaries

Author: pproenca

.github/workflows/ci.yml

@@ -205,7 +205,7 @@ jobs:
         run: npx tsx scripts/ci/ci-workflow.ts extract-ffmpeg --archive "ffmpeg-${{ matrix.platform }}.tar.gz" --out ffmpeg-install
 
       - name: Build with prebuildify
-        run: npx tsx scripts/ci/ci-workflow.ts prebuildify --arch "${{ matrix.arch }}" --platform "${{ matrix.platform }}"
+        run: npx tsx scripts/ci/ci-workflow.ts prebuildify --arch "${{ matrix.arch }}" --platform "${{ matrix.platform }}"${{ runner.os == 'Linux' && ' --libc glibc' || '' }}
 
       - name: Build TypeScript
         run: npm run build:ts
@@ -218,20 +218,21 @@ jobs:
           PLATFORM: ${{ matrix.platform }}
           PLATFORM_OS: ${{ runner.os == 'macOS' && 'darwin' || 'linux' }}
           PLATFORM_CPU: ${{ matrix.arch }}
-        run: npx tsx scripts/ci/ci-workflow.ts package-platform --platform "$PLATFORM" --os "$PLATFORM_OS" --cpu "$PLATFORM_CPU" --prebuild "prebuilds/${{ matrix.platform }}/node.napi.node" --out packages
+          PLATFORM_LIBC: ${{ runner.os == 'Linux' && 'glibc' || '' }}
+        run: npx tsx scripts/ci/ci-workflow.ts package-platform --platform "$PLATFORM" --os "$PLATFORM_OS" --cpu "$PLATFORM_CPU" --prebuild "prebuilds/${{ matrix.platform }}/node.napi.node" --out packages${{ runner.os == 'Linux' && ' --libc glibc' || '' }}
 
       - name: Upload platform package artifact
         uses: actions/upload-artifact@v6
         with:
-          name: platform-pkg-${{ matrix.platform }}
-          path: packages/@pproenca-node-webcodecs-${{ matrix.platform }}.tar
+          name: platform-pkg-${{ matrix.platform }}${{ runner.os == 'Linux' && '-glibc' || '' }}
+          path: packages/@pproenca-node-webcodecs-${{ matrix.platform }}${{ runner.os == 'Linux' && '-glibc' || '' }}.tar
           retention-days: 14 # Extended for release timing flexibility
           compression-level: 0
 
       - name: Attest platform package
         uses: actions/attest-build-provenance@v3
         with:
-          subject-path: packages/@pproenca/node-webcodecs-${{ matrix.platform }}/bin/node.napi.node
+          subject-path: packages/@pproenca/node-webcodecs-${{ matrix.platform }}${{ runner.os == 'Linux' && '-glibc' || '' }}/bin/node.napi.node
 
   # ============================================================================
   # Test Node version compatibility using prebuilt binaries