Rewrite in Go: static binaries, zero runtime dependencies

Replace Node.js + Python codebase with three Go binaries:
- claude-statusline: CLI status bar for Claude Code
- claude-fetcher: standalone cron job for API usage
- claude-widget: system tray icon (fyne-io/systray + fogleman/gg)

All CGO-free for trivial cross-compilation. Add nfpm .deb packaging
with autostart and cron. CI pipeline produces Linux + Windows binaries,
.deb, .tar.gz, and .zip release assets.

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

.gitignore

@@ -1,9 +1,16 @@
-__pycache__/
-*.pyc
-*.pyo
-*.egg-info/
+# Go binaries
+claude-statusline
+claude-fetcher
+claude-widget
+*.exe
+
+# Build output
 dist/
-build/
-.venv/
-venv/
-node_modules/
+dist-win/
+*.deb
+*.tar.gz
+*.zip
+
+# IDE
+.idea/
+.vscode/