verifier, uraniborg: batch verification; faster, cancellable proof check

[billy-lau]

Checking each APK split with its own verifier run fetched the checkpoint and searched the log once per split, so the proof step took minutes.

• verifier: add --payloads_path batch mode. It searches each log once for all payloads and shares hash tiles between proofs. Results stream as JSON Lines and match single-payload runs, even if a tile download fails.
• inclusion_proof_check.py: use batch mode. Splits it gives no result for (old or crashed verifier) are checked one at a time; an old verifier also triggers a warning to rebuild it. A missing verifier is reported once, not once per split.
• Report step_progress events, add package and split labels to log lines, and kill the running verifier on Ctrl-C or SIGTERM.

314 splits on an Android 14 emulator: proof step ~9 s instead of minutes. Results match per-split runs exactly.

Test: go test ./... (new batch, tile-error and cancellation tests);
pytest tests (185 pass); emulator run; old-verifier fallback run.

Change-Id: I1b1b9b69fdd6f3d51ac75ebc803725187343ff6c