fix: Make Mayor/Deacon session names include town name

Session names `gt-mayor` and `gt-deacon` were hardcoded, causing tmux
session name collisions when running multiple towns simultaneously.

Changed to `gt-{town}-mayor` and `gt-{town}-deacon` format (e.g.,
`gt-ai-mayor`) to allow concurrent multi-town operation.

Key changes:
- session.MayorSessionName() and DeaconSessionName() now take townName param
- Added workspace.GetTownName() helper to load town name from config
- Updated all callers in cmd/, daemon/, doctor/, mail/, rig/, templates/
- Updated tests with new session name format
- Bead IDs remain unchanged (already scoped by .beads/ directory)

Fixes #60

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

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

internal/cmd/polecat_cycle.go

@@ -88,8 +88,16 @@ func parsePolecatSessionName(sessionName string) (rigName, polecatName string, o
 		return "", "", false
 	}
 
-	// Exclude town-level sessions
-	if sessionName == "gt-mayor" || sessionName == "gt-deacon" {
+	// Exclude town-level sessions by exact match
+	mayorSession, _ := getMayorSessionName()
+	deaconSession, _ := getDeaconSessionName()
+	if sessionName == mayorSession || sessionName == deaconSession {
+		return "", "", false
+	}
+
+	// Also exclude by suffix pattern (gt-{town}-mayor, gt-{town}-deacon)
+	// This handles cases where town config isn't available
+	if strings.HasSuffix(sessionName, "-mayor") || strings.HasSuffix(sessionName, "-deacon") {
 		return "", "", false
 	}