feat: add Cobra CLI scaffolding with Lipgloss styles

- cmd/gt/main.go: Entry point using Cobra
- internal/cmd/root.go: Root command with description
- internal/cmd/version.go: Version command with build info
- internal/style/style.go: Lipgloss styles for terminal output

Closes gt-u1j.1

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

go.mod

@@ -1,3 +1,21 @@
 module github.com/steveyegge/gastown
 
 go 1.23
+
+require (
+	github.com/charmbracelet/lipgloss v1.0.0
+	github.com/spf13/cobra v1.8.1
+)
+
+require (
+	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
+	github.com/charmbracelet/x/ansi v0.4.2 // indirect
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/mattn/go-runewidth v0.0.15 // indirect
+	github.com/muesli/termenv v0.15.2 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	golang.org/x/sys v0.19.0 // indirect
+)