Preserve busy ComfyUI jobs and talking-head review lane

[stone84949]

Summary

This draft contains three scoped commits:

1. ComfyUI busy-server resilience — increases health/model-discovery/poll request allowances for model-loading pauses.
2. Talking-head review lane preservation — retains the existing review-lane runner, deterministic opening-window selection, subtitle/export support, QA coverage, and template note in canonical history.
3. Bounded retry correction — narrows poll retries to transient timeout/connection failures, caps each history request and sleep to the remaining caller deadline, propagates HTTP status failures immediately, and removes unrelated historical pilot/starter-lane payload from this PR.

User impact

Large ComfyUI workflows can survive temporary unresponsive periods while models load, without exceeding the caller's requested wait budget. A real HTTP failure is surfaced immediately instead of being misreported as a busy server. The talking-head review path remains reproducible and now has a mocked lane-level regression contract.

Safety boundary

• No provider, model, workflow-selection, or new video-pipeline behavior was added in this corrective round.
• Only requests.Timeout and requests.ConnectionError are retried; HTTP errors and other request failures propagate.
• The existing caller timeout remains the hard upper bound for both polling requests and sleeps.
• Historical pilot notes, a generic starter-lane plan, a misnamed prose .json, and an empty payload file were removed from the final PR diff.

Validation

.venv\\Scripts\\python.exe -m pytest tests/contracts/test_comfyui_tools.py -q
# 70 passed

.venv\\Scripts\\python.exe -m pytest tests/qa/test_09_talking_head_review_lane.py -q
# 2 passed

.venv\\Scripts\\python.exe -m pytest tests/contracts/test_phase1_contracts.py -q
# 69 passed

.venv\\Scripts\\python.exe -m py_compile tools\\_comfyui\\client.py lib\\talking_head_review_lane.py scripts\\run_talking_head_review_lane.py tests\\contracts\\test_comfyui_tools.py tests\\qa\\test_09_talking_head_review_lane.py

git diff --check origin/main...HEAD