RAI-273: simulated week runner (40 shops, 7 days, worker kills, soak)

Part of RAI-273 (the simulated week); the console wiring and Sheets export in that issue are not in this PR. Draft for review.

What

python -m mimi.api.week: one synthetic distributor (Coral Lane) and its 40 shops for a full Lagos week through the real HTTP API, the durable store and real worker processes, with forced SIGKILLs, webhook replays and a soak mode. Scored from the store. Docs: docs/WEEK.md. Reports: docs/runs/week-offline.*, docs/runs/soak-offline.*.

Numbers (offline, ₦0, seed 273, SQLite, 2 workers)

Four bugs the week found (fixed here)

1. mimi/harness/binding.py: "ok noted", "seen", a thumbs up on an open delivery receipt went to small talk and the receipt stayed open. Non-greeting small talk on an open ask now binds as "unclear" (one ask again); a greeting alone still releases.
2. mimi/harness/lexicon.py: "Which shops owe me the most?" was a money misroute to the low-stock report. New collector/chase phrase rule.
3. mimi/harness/loop.py: the budget_hit trace now carries max_kobo and reserve_kobo, so every figure in the owner's budget note is in the trace.
4. mimi/proof/tools.py: a resent screenshot (same content-hash proof id) skipped its own original, was checked as new, and after the invoice was paid failed time_after_delivery and was flagged fake. The original is now kept as prior proof. Regression in tests/test_api_helpers.py.

CI

New step in the test job: one simulated day, 2 workers, 1 forced kill (--days 1 --workers 2 --week-kills 1 --no-write, ~26 s locally). make week, make week-day, make week-soak added.

Open items

• One fewer model call per ask turn: needs Tobi's yes and a paid re-record of the recorded answers.
• The 6 h soak with 20 kills and a live week (--live --max-naira): need a budget yes.
• Known gaps (in docs/WEEK.md): fakes f06/f07 excluded (their tell needs another shop's prior proof the week cannot set up); offline routing misses on the refund probe and one unreadable caption (still refused, no money moves); lease takeovers under load with the 3 s week lease.