feat(tui): persona surface — sticky header + TabPane (v0.13.0)

Step 3 of the Worldtree #204 integration: visible persona-state UX.
Pairs with v0.11.0's AffectUpdate SSE event + v0.12.0's
get_persona_state HTTP client — together those gave the data; this
bump surfaces it.

Two surfaces (Option C: both):

Sticky persona-header (top of screen, dock=top, height=1):
- Shape: `agent_id · dominant_emotion · pad(P, A, D) · N emotions
  active` — concise enough for at-a-glance scan above the chat
- Starts hidden via `.empty` CSS class; height collapses to 0 when
  the agent has no persona surface
- Refreshes on AffectUpdate(status="current") snapshots

Persona TabPane (Ctrl+4):
- Full snapshot detail: dominant emotion, PAD axes with baseline +
  delta, mood drift, active emotions with intensity + decay
  (minutes-rounded), last_updated_at footer
- Replaced (not appended) on each new snapshot — snapshots are
  absolute state, not incremental

Lifecycle:
- on_mount spawns a Textual worker that calls get_persona_state to
  hydrate header + pane before turn 1
- PersonaNotConfigured (domari, muninn, Tier 3) → pane carries an
  italic placeholder, header stays empty
- AgentNotAvailable / AuthScopeDenied / network error → italic
  failure placeholder; audit-logged; never crashes
- Presenter's render() takes an optional `on_persona_snapshot`
  callback so AffectUpdate(current) refreshes both surfaces during
  a live turn (no widget coupling — App owns the callback)

Tests: 10 new (4 formatters, 3 presenter callback, 4 layout/binding/
hydration). Full suite: 313 passing.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "ratatoskr"
-version = "0.12.0"
+version = "0.13.0"
 description = "Worldtree Conversation API debug TUI — multi-pane observability dashboard"
 readme = "README.md"
 requires-python = ">=3.12"