feat(tmux): add per-rig color themes and dynamic status line (gt-vc1n)

Add tmux status bar theming for Gas Town sessions:

- Per-rig color themes auto-assigned via consistent hashing
- 10 curated dark themes (ocean, forest, rust, plum, etc.)
- Special gold/dark theme for Mayor
- Dynamic status line showing current issue and mail count
- Mayor status shows polecat/rig counts

New commands:
- gt theme --list: show available themes
- gt theme apply: apply to running sessions
- gt issue set/clear: agents update their current issue
- gt status-line: internal command for tmux refresh

Status bar format:
- Left: [rig/worker] role
- Right: <issue> | <mail> | HH:MM

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

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

internal/daemon/lifecycle.go

@@ -6,6 +6,8 @@ import (
 	"os/exec"
 	"strings"
 	"time"
+
+	"github.com/steveyegge/gastown/internal/tmux"
 )
 
 // BeadsMessage represents a message from beads mail.
@@ -177,13 +179,14 @@ func (d *Daemon) identityToSession(identity string) string {
 func (d *Daemon) restartSession(sessionName, identity string) error {
 	// Determine working directory and startup command based on agent type
 	var workDir, startCmd string
+	var rigName string
 
 	if identity == "mayor" {
 		workDir = d.config.TownRoot
 		startCmd = "exec claude --dangerously-skip-permissions"
 	} else if strings.HasSuffix(identity, "-witness") {
 		// Extract rig name: <rig>-witness → <rig>
-		rigName := strings.TrimSuffix(identity, "-witness")
+		rigName = strings.TrimSuffix(identity, "-witness")
 		workDir = d.config.TownRoot + "/" + rigName
 		startCmd = "exec claude --dangerously-skip-permissions"
 	} else {
@@ -198,6 +201,15 @@ func (d *Daemon) restartSession(sessionName, identity string) error {
 	// Set environment
 	_ = d.tmux.SetEnvironment(sessionName, "GT_ROLE", identity)
 
+	// Apply theme
+	if identity == "mayor" {
+		theme := tmux.MayorTheme()
+		_ = d.tmux.ConfigureGasTownSession(sessionName, theme, "", "Mayor", "coordinator")
+	} else if rigName != "" {
+		theme := tmux.AssignTheme(rigName)
+		_ = d.tmux.ConfigureGasTownSession(sessionName, theme, rigName, "witness", "witness")
+	}
+
 	// Send startup command
 	if err := d.tmux.SendKeys(sessionName, startCmd); err != nil {
 		return fmt.Errorf("sending startup command: %w", err)