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

ui/src/style.css

@@ -123,6 +123,7 @@ body { margin: 0; background: var(--paper); color: var(--ink); font: 500 17px/1.
 .tile.has-pending { background: rgb(155 47 34 / 0.06); }
 .tile-text { min-width: 0; }
 .tile-name { margin: 0; font: 400 16px/1.15 var(--display); }
+.epithet { font: italic 500 14px/1 var(--body); color: var(--muted); }
 .update {
   margin: 3px 0 0; font: italic 500 14px/1.3 var(--body); color: var(--muted);
   white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
@@ -224,6 +225,14 @@ body { margin: 0; background: var(--paper); color: var(--ink); font: 500 17px/1.
 .reaction.good, .reaction.auto { color: var(--ink); }
 .reaction.bad { color: var(--red); }
 
+/* Banter: a quiet aside between crows, smaller and set in from the work. */
+.msg.banter { grid-template-columns: 26px 1fr; gap: 0 10px; padding-top: 4px; padding-bottom: 8px; padding-left: 82px; }
+.msg.banter .avatar { width: 26px; height: 24px; margin-top: 1px; }
+.banter-line { margin: 0; font-size: 15px; }
+.banter-who { display: block; font: 400 13px/1.2 var(--display); color: var(--muted); }
+.banter-text { font-style: italic; }
+@media (max-width: 759px) { .msg.banter { padding-left: 60px; } }
+
 .msg.system { display: block; padding: 12px 28px; text-align: center; color: var(--muted); font-style: italic; font-size: 15px; }
 .msg.system p { margin: 0; }
 .msg.system.sparkle p::before {