Put every S3 URI in one place, and add a lint gate

Five workers built output URIs with inline f-strings, so the bucket-per-artifact
layout was spread across worker_tts, worker_identity, worker_crop, worker_layers
and worker_render. Moving a class between buckets meant a grep. They are now
templates in transport.py, formatted at each call site.

Three of those workers also each reimplemented the same parse to recover
manga_id and chapter_id from an input uri, because the orchestrator does not
send them. That is transport.ids_from_uri now, and it raises on a uri too short
to carry the ids rather than returning a wrong pair.

ruff.toml makes `ruff check .` exit 0, so CI can gate on it and a new finding
means a new defect. Fixed: an implicit Optional in 8 signatures, an unparenthesized
implicit concatenation in the ASS filter list, 5 subprocess.run calls now saying
check=False out loud, an unused import, a duplicate exception handler and a
non-executable shebang. Every rule left off carries its reason in ruff.toml.

The ASYNC rules are off because ffmpeg on the event loop is real and already
recorded at caveats/audit-open.md#blocking-event-loop. It needs a refactor per
handler, not a lint fix.

Checked: transport, collage, bubble_detect, test_vision_parse, worker_crop,
worker_scene, worker_script, worker_identity, worker_tts, session_manager,
worker_vision and worker_render self-checks all pass. worker_layers still fails
on a missing legacy/qwen_layered_workflow.json, which predates this branch.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

bubble_detect.py

@@ -38,7 +38,7 @@ def _letterbox(img, sz=1024):
     return canvas, r, px, py
 
 
-def detect_text_regions(img, conf: float = None) -> list:
+def detect_text_regions(img, conf: float | None = None) -> list:
     """img: BGR ndarray (one panel). -> [{"bbox":[x1,y1,x2,y2], "conf":float}] in ORIGINAL pixels,
     reading order (top->bottom, left->right). Empty list on no detections (caller falls back to the
     holistic prompt). Load + inference are lazy so importing this never touches the GPU or the model."""