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/doctor/orphan_check.go

@@ -8,7 +8,9 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/steveyegge/gastown/internal/session"
 	"github.com/steveyegge/gastown/internal/tmux"
+	"github.com/steveyegge/gastown/internal/workspace"
 )
 
 // OrphanSessionCheck detects orphaned tmux sessions that don't match
@@ -55,24 +57,31 @@ func (c *OrphanSessionCheck) Run(ctx *CheckContext) *CheckResult {
 	// Get list of valid rigs
 	validRigs := c.getValidRigs(ctx.TownRoot)
 
+	// Get dynamic session names for mayor/deacon
+	var mayorSession, deaconSession string
+	if townName, err := workspace.GetTownName(ctx.TownRoot); err == nil {
+		mayorSession = session.MayorSessionName(townName)
+		deaconSession = session.DeaconSessionName(townName)
+	}
+
 	// Check each session
 	var orphans []string
 	var validCount int
 
-	for _, session := range sessions {
-		if session == "" {
+	for _, sess := range sessions {
+		if sess == "" {
 			continue
 		}
 
 		// Only check gt-* sessions (Gas Town sessions)
-		if !strings.HasPrefix(session, "gt-") {
+		if !strings.HasPrefix(sess, "gt-") {
 			continue
 		}
 
-		if c.isValidSession(session, validRigs) {
+		if c.isValidSession(sess, validRigs, mayorSession, deaconSession) {
 			validCount++
 		} else {
-			orphans = append(orphans, session)
+			orphans = append(orphans, sess)
 		}
 	}
 
@@ -166,27 +175,27 @@ func (c *OrphanSessionCheck) getValidRigs(townRoot string) []string {
 
 // isValidSession checks if a session name matches expected Gas Town patterns.
 // Valid patterns:
-//   - gt-mayor
-//   - gt-deacon
+//   - gt-{town}-mayor (dynamic based on town name)
+//   - gt-{town}-deacon (dynamic based on town name)
 //   - gt-<rig>-witness
 //   - gt-<rig>-refinery
 //   - gt-<rig>-<polecat> (where polecat is any name)
 //
 // Note: We can't verify polecat names without reading state, so we're permissive.
-func (c *OrphanSessionCheck) isValidSession(session string, validRigs []string) bool {
-	// gt-mayor is always valid
-	if session == "gt-mayor" {
+func (c *OrphanSessionCheck) isValidSession(sess string, validRigs []string, mayorSession, deaconSession string) bool {
+	// Mayor session is always valid (dynamic name based on town)
+	if mayorSession != "" && sess == mayorSession {
 		return true
 	}
 
-	// gt-deacon is always valid
-	if session == "gt-deacon" {
+	// Deacon session is always valid (dynamic name based on town)
+	if deaconSession != "" && sess == deaconSession {
 		return true
 	}
 
 	// For rig-specific sessions, extract rig name
 	// Pattern: gt-<rig>-<role>
-	parts := strings.SplitN(session, "-", 3)
+	parts := strings.SplitN(sess, "-", 3)
 	if len(parts) < 3 {
 		// Invalid format - must be gt-<rig>-<something>
 		return false