docs: improve help text and add nudge documentation

Polish help text across all agent commands to clarify roles:
- crew: persistent workspaces vs ephemeral polecats
- deacon: town-level watchdog receiving heartbeats
- dog: cross-rig infrastructure workers (cats vs dogs)
- mayor: Chief of Staff for cross-rig coordination
- nudge: universal synchronous messaging API
- polecat: ephemeral one-task workers, self-cleaning
- refinery: merge queue serializer per rig
- witness: per-rig polecat health monitor

Add comprehensive gt nudge documentation to crew template explaining
when to use nudge vs mail, common patterns, and target shortcuts.

Add orphan-process-cleanup step to deacon patrol formula to clean up
claude subagent processes that fail to exit (TTY = "?").

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

internal/cmd/mayor.go

@@ -16,12 +16,20 @@ var mayorCmd = &cobra.Command{
 	Use:     "mayor",
 	Aliases: []string{"may"},
 	GroupID: GroupAgents,
-	Short:   "Manage the Mayor session",
+	Short:   "Manage the Mayor (Chief of Staff for cross-rig coordination)",
 	RunE:    requireSubcommand,
-	Long: `Manage the Mayor tmux session.
+	Long: `Manage the Mayor - the Overseer's Chief of Staff.
 
-The Mayor is the global coordinator for Gas Town, running as a persistent
-tmux session. Use the subcommands to start, stop, attach, and check status.`,
+The Mayor is the global coordinator for Gas Town:
+  - Receives escalations from Witnesses and Deacon
+  - Coordinates work across multiple rigs
+  - Handles human communication when needed
+  - Routes strategic decisions and cross-project issues
+
+The Mayor is the primary interface between the human Overseer and the
+automated agents. When in doubt, escalate to the Mayor.
+
+Role shortcuts: "mayor" in mail/nudge addresses resolves to this agent.`,
 }
 
 var mayorAgentOverride string