Add cross-platform packaging, icons, and Claude Code config discovery

- Auto-discovers Claude Code (~/.claude/settings.json) alongside Claude Desktop
- Generated icons/app.icns (macOS) and icons/app.ico (Windows) from rounded PNGs
- bcc.spec: PyInstaller spec for all platforms (.app on macOS, onefile on Windows/Linux)
- .github/workflows/release.yml: builds and publishes GitHub Release on version tags
- scripts/build_icons.py: regenerates icon files from source PNGs
- requirements-dev.txt: adds pyinstaller and pillow for building
- CLAUDE.md: initial repo guidance for Claude Code

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

requirements-dev.txt

@@ -0,0 +1,6 @@
+# Runtime (also in requirements.txt)
+PySide6>=6.6
+
+# Build / packaging
+pyinstaller>=6.0
+pillow>=10.0        # generates icons/app.ico during CI (Windows build)