fix: Detect mayor role from any rig's mayor/ folder (gt-0nh8)

Previously gt prime only detected the Mayor role from town root (~/gt) or
~/gt/mayor/. Now it also detects Mayor from <rig>/mayor/ paths like
~/gt/gastown/mayor/rig, enabling mayor sessions to work correctly
regardless of which rig directory they're attached to.

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

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

internal/cmd/prime.go

@@ -38,7 +38,7 @@ var primeCmd = &cobra.Command{
 	Long: `Detect the agent role from the current directory and output context.
 
 Role detection:
-  - Town root or mayor/rig/ → Mayor context
+  - Town root, mayor/, or <rig>/mayor/ → Mayor context
   - <rig>/witness/rig/ → Witness context
   - <rig>/refinery/rig/ → Refinery context
   - <rig>/polecats/<name>/ → Polecat context
@@ -186,6 +186,12 @@ func detectRole(cwd, townRoot string) RoleInfo {
 	rigName := parts[0]
 	ctx.Rig = rigName
 
+	// Check for mayor: <rig>/mayor/ or <rig>/mayor/rig/
+	if len(parts) >= 2 && parts[1] == "mayor" {
+		ctx.Role = RoleMayor
+		return ctx
+	}
+
 	// Check for witness: <rig>/witness/rig/
 	if len(parts) >= 2 && parts[1] == "witness" {
 		ctx.Role = RoleWitness