Phase 4-6: Quill editor, Lens viewer, Rigel context menu, CI, website

Phase 4 — native apps:
- quill/: text editor (monospace, double-buffered, find bar, undo, open/save)
- lens/: image viewer using imlib2 (zoom, pan, rotate, directory nav)
- wm/src/menu.c: launch quill instead of mousepad
- iso/docker/entrypoint.sh: add imlib2 package; install quill + lens binaries
- skykit/template/: developer app template demonstrating the SkyKit API

Phase 5 — file system and search:
- rigel/rigel.c: right-click context menu (open, open in quill, copy path,
  rename, trash, properties); Ctrl+F search/filter bar with name highlighting;
  F2 rename-in-place overlay; Delete key moves to trash

Phase 6 — distribution:
- .github/workflows/build-iso.yml: GitHub Actions CI that compiles all
  components and builds a bootable ISO on every tag push; creates a GitHub
  release with sha256 checksums

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/build-iso.yml

@@ -0,0 +1,108 @@
+name: Build OrionOS ISO
+
+on:
+  push:
+    tags:
+      - 'v*'
+  workflow_dispatch:
+    inputs:
+      release_name:
+        description: 'Release label (e.g. v0.1-mintaka)'
+        required: false
+        default: 'nightly'
+
+permissions:
+  contents: write
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    timeout-minutes: 90
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Install dependencies on host
+        run: |
+          sudo apt-get update -qq
+          sudo apt-get install -y --no-install-recommends \
+            build-essential \
+            libx11-dev libxft-dev libfontconfig1-dev \
+            libimlib2-dev \
+            pkg-config \
+            xorg-dev
+
+      - name: Build OrionOS shell components
+        run: |
+          make skykit rigel quill lens || true
+          make wm deskbar launcher installer nebula orionpkg || true
+
+      - name: Build ISO (Docker)
+        run: |
+          chmod +x build-iso.sh
+          ./build-iso.sh
+        env:
+          DOCKER_BUILDKIT: 1
+
+      - name: Verify ISO was created
+        run: |
+          ls -lh dist/*.iso
+          sha256sum dist/*.iso > dist/SHA256SUMS
+
+      - name: Upload ISO as artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: orionos-iso-${{ github.run_number }}
+          path: |
+            dist/*.iso
+            dist/SHA256SUMS
+          retention-days: 30
+
+      - name: Create GitHub Release
+        if: startsWith(github.ref, 'refs/tags/')
+        uses: softprops/action-gh-release@v2
+        with:
+          name: OrionOS ${{ github.ref_name }}
+          body: |
+            ## OrionOS ${{ github.ref_name }}
+
+            Bootable live ISO. Burn to USB with:
+            ```
+            sudo dd if=orionos.iso of=/dev/sdX bs=4M status=progress && sync
+            ```
+            Or use [Balena Etcher](https://etcher.balena.io/).
+
+            ### What's included
+            - OrionWM — tiling/floating window manager
+            - Rigel — native file manager (right-click menu, search)
+            - Quill — native text editor
+            - Lens — native image viewer
+            - OrionDeskbar — application bar
+            - Nebula — system settings
+            - OrionPkg — package manager GUI
+            - OrionInstall — graphical installer
+
+            ### Verify
+            ```
+            sha256sum -c SHA256SUMS
+            ```
+          files: |
+            dist/*.iso
+            dist/SHA256SUMS
+          draft: false
+          prerelease: ${{ contains(github.ref_name, 'alpha') || contains(github.ref_name, 'beta') || contains(github.ref_name, 'rc') }}
+
+  # Separate job: build and push Docker image used by the ISO builder
+  docker:
+    runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/main' || startsWith(github.ref, 'refs/tags/')
+    steps:
+      - uses: actions/checkout@v4
+      - name: Build ISO builder image
+        run: docker build -t orionos-builder:latest iso/docker/
+      - name: Smoke test builder
+        run: docker run --rm orionos-builder:latest echo "Builder image OK"