feat(sse,tui): bump spec pin to v0.29.0 + AwaitingLlmFirstToken (v0.14.0)

Spec pin moved da93ca7 (v0.28.0) → 562001a (v0.29.0); vendored
conversation-api-spec.md + conversation_api.contract.md re-snapshotted.
The only material delta is Worldtree #201's awaiting_llm_first_token
SSE heartbeat — a top-level event (NOT a worker_phase extension, per
INV-053's three-field stability) that fires at a configurable interval
(default 5s) during the BuildingPrompt → CallingLLM gap.

Wire layer (sse_client.py):
- New `AwaitingLlmFirstToken` dataclass: sse_id / turn_id /
  elapsed_ms_since_building_prompt (server-authoritative monotonic)
- Added to Event union + _envelope_for_type dispatch branch
- Without this, ratatoskr would crash on any slow-first-token turn
  from a v0.29.0 server (unknown SSE event type → ValueError)

TUI layer (tui.py):
- Audit pipeline: per-event debug-pane line with elapsed in seconds
- Live transcript indicator: first heartbeat mounts a Static
  ("awaiting first token · 5.0s"); subsequent heartbeats update it
  in place; any non-heartbeat event removes it (the gap closed)
- Turn-summary line now carries heartbeat count
- Indicator demoted via .awaiting-label CSS so it reads as ambient
  progress, not content

Tests: 2 wire-layer (single + monotonic sequence) + 3 presenter
(audit line shape, single-mount semantic, indicator removal on gap
close). Suite: 318 passing.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "ratatoskr"
-version = "0.13.0"
+version = "0.14.0"
 description = "Worldtree Conversation API debug TUI — multi-pane observability dashboard"
 readme = "README.md"
 requires-python = ">=3.12"
@@ -42,9 +42,9 @@ Repository = "https://gitea.phasefinal.com/vh/ratatoskr"
 # Ratatoskr is built against Worldtree at this commit; the vendored
 # spec snapshot in docs/ reflects that SHA.
 [tool.ratatoskr.spec-pin]
-worldtree-spec-rev = "da93ca7cf613f1dc229a7a44d07fc1d7efc78e25"
-worldtree-version = "v0.28.0"
-pinned-on = "2026-05-25"
+worldtree-spec-rev = "562001af28d752c3a60d449c7ddd09f44fa9dc9a"
+worldtree-version = "v0.29.0"
+pinned-on = "2026-05-26"
 
 [tool.hatch.build.targets.wheel]
 packages = ["src/ratatoskr"]