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>

go.mod

@@ -0,0 +1,15 @@
+module git.davoryn.de/calic/claude-statusline
+
+go 1.21
+
+require (
+	fyne.io/systray v1.11.0
+	github.com/fogleman/gg v1.3.0
+)
+
+require (
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
+	golang.org/x/image v0.18.0 // indirect
+	golang.org/x/sys v0.15.0 // indirect
+)