Adoption matched on the pool and a health probe, and the registry recorded
nothing about what the pod was RUNNING. Two silent mistakes followed from that:

* **the image.** The same model on a pinned tag and on `:latest` is different
  code. A pool configured for one could inherit a pod running the other, and
  nothing in the system could tell — which is precisely the confusion that cost
  a whole evening today: an OCR result was attributed to code that was not what
  the pod was running.
* **the card.** A pod rented as a FALLBACK is on a card the configuration
  accepts only when its preferred one is unavailable. Inheriting one would serve
  a lease that asked for an A40 *and nothing else* (v0.3.54) from an RTX A6000 —
  the exact comparison that feature exists to protect. Live tonight the pool had
  both: an adopted A40 and a rented A6000 fallback for one model.

So `register_pod` records the image and the card at creation (and keeps them
across a re-registration, since an adopting owner does not know them), and
`find_shared_pod` takes `image` and `gpus` and refuses anything that does not
match, naming the pod and the reason. The one caller passes the image from the
plan it would launch and the cards from `narrow_gpu_choice` — so a client
lease's narrowing constrains adoption exactly as it constrains renting.

An entry recording neither field is refused rather than trusted: refusing costs
one extra pod once and the old one is reaped, while trusting costs a silent
answer from the wrong code. A caller that names neither constraint keeps the old
behaviour, so this adds constraints without adding requirements.

Also here: an adopted pod is now billed from when it was CREATED, not from when
it was taken over. `_terminate` computes the spend from `started_at`, which
adoption set to "now" — so a pod created at 22:27 and adopted at 23:10 was
ledgered for 16 minutes of an hour's life, and the rest was charged to nobody.
The registry already records `created`, and only cost and uptime reporting read
`started_at`.

11 tests in tests/test_adoption_matches_image_and_card.py, one more in
tests/test_pod_token_adoption_race.py.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PxYHWbCAjjjD7A1rhFKtaW