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/town_cycle.go

@@ -6,6 +6,7 @@ import (
 	"sort"
 
 	"github.com/spf13/cobra"
+	"github.com/steveyegge/gastown/internal/workspace"
 )
 
 // townCycleSession is the --session flag for town next/prev commands.
@@ -13,9 +14,32 @@ import (
 // correct, so we pass the session name explicitly via #{session_name} expansion.
 var townCycleSession string
 
-// Town-level sessions that participate in cycling (mayor, deacon).
-// These are the session names without the "gt-" prefix.
-var townLevelSessions = []string{"gt-mayor", "gt-deacon"}
+// getTownLevelSessions returns the town-level session names for the current workspace.
+// Returns empty slice if workspace cannot be determined.
+func getTownLevelSessions() []string {
+	mayorSession, errMayor := getMayorSessionName()
+	deaconSession, errDeacon := getDeaconSessionName()
+	if errMayor != nil || errDeacon != nil {
+		return nil
+	}
+	return []string{mayorSession, deaconSession}
+}
+
+// isTownLevelSession checks if the given session name is a town-level session.
+func isTownLevelSession(sessionName string) bool {
+	townRoot, err := workspace.FindFromCwd()
+	if err != nil || townRoot == "" {
+		return false
+	}
+	townName, err := workspace.GetTownName(townRoot)
+	if err != nil {
+		return false
+	}
+	mayorSession, _ := getMayorSessionName()
+	deaconSession, _ := getDeaconSessionName()
+	_ = townName // used for session name generation
+	return sessionName == mayorSession || sessionName == deaconSession
+}
 
 func init() {
 	rootCmd.AddCommand(townCmd)
@@ -78,15 +102,7 @@ func cycleTownSession(direction int, sessionOverride string) error {
 	}
 
 	// Check if current session is a town-level session
-	isTownSession := false
-	for _, s := range townLevelSessions {
-		if s == currentSession {
-			isTownSession = true
-			break
-		}
-	}
-
-	if !isTownSession {
+	if !isTownLevelSession(currentSession) {
 		// Not a town session - no cycling, just stay put
 		return nil
 	}
@@ -145,6 +161,12 @@ func findRunningTownSessions() ([]string, error) {
 		return nil, fmt.Errorf("listing tmux sessions: %w", err)
 	}
 
+	// Get town-level session names
+	townLevelSessions := getTownLevelSessions()
+	if townLevelSessions == nil {
+		return nil, fmt.Errorf("cannot determine town-level sessions")
+	}
+
 	var running []string
 	for _, line := range splitLines(string(out)) {
 		if line == "" {