Crow personas and generated banter

- personas.go: backstory, prompt policy and output policy per crow;
  Hugin and Munin grounded in Grimnismal 20 and Gylfaginning 38;
  every working crow also follows a common output policy
- Personas go into each crow's instructions; Sentry keeps JSON-only
- banter.go: retrieve backstory, relationships and recent flock
  memory, then the speaking crow generates one line in character;
  max 2 per list against the list budget, never blocks work,
  unusable lines dropped
- crow.banter event, GET /api/crows, `crows personas` -> PERSONAS.md
- UI: epithets on tiles and messages, banter as quiet asides

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UQnSw4RRWp8uqpj3nsnnXF

main.go

@@ -28,6 +28,8 @@ func main() {
 		cmdTrust()
 	case "log":
 		cmdLog(os.Args[2:])
+	case "personas":
+		fmt.Print(personaSheet())
 	default:
 		usage()
 	}
@@ -39,7 +41,8 @@ func usage() {
   crows run <todo.txt> [-as name] [-nest id]  hand the flock a todo list
   crows serve [-addr 127.0.0.1:8080] run the web server (API + SSE)
   crows trust                       show trust ledger
-  crows log [-n 20]                 show recent flight log entries`)
+  crows log [-n 20]                 show recent flight log entries
+  crows personas                    print the flock's persona sheet (Markdown)`)
 	os.Exit(2)
 }