Remove standalone fetcher, add setup tool with install/uninstall workflow

Drop claude-fetcher binary and cron job — the widget's built-in
BackgroundFetcher is the sole fetcher now. Add cmd/setup with cross-platform
install and uninstall (--uninstall): kills widget, removes binaries + autostart,
cleans Claude Code statusline setting, optionally removes config dir.

Also includes: browser-based login (chromedp), ICO wrapper for Windows tray
icon, and reduced icon size (64px).

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

go.mod

@@ -1,15 +1,22 @@
 module git.davoryn.de/calic/claude-statusline
 
-go 1.21
+go 1.24
 
 require (
 	fyne.io/systray v1.11.0
+	github.com/chromedp/cdproto v0.0.0-20250724212937-08a3db8b4327
+	github.com/chromedp/chromedp v0.14.2
 	github.com/fogleman/gg v1.3.0
 )
 
 require (
+	github.com/chromedp/sysutil v1.1.0 // indirect
+	github.com/go-json-experiment/json v0.0.0-20250725192818-e39067aee2d2 // indirect
+	github.com/gobwas/httphead v0.1.0 // indirect
+	github.com/gobwas/pool v0.2.1 // indirect
+	github.com/gobwas/ws v1.4.0 // indirect
 	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
+	golang.org/x/sys v0.34.0 // indirect
 )