feat(plane): honest coverage in alerts; PHP alerts from the engine on the host

Quick mode has rules only for c/cpp, groovy, java, javascript/typescript and
python, so every PHP case's "0 alerts" read as clean. The `alerts` task now
records per language of the files read whether quick mode covers it
(derived from the bundled ruleset, not a list): coverage quick | none, with
file counts per pin, and `uncovered`. `remember` turns that into `coverage`
memory rows (a new kind; the Run passes the alerts summary.json as input),
loop-measure reports coverage per language, and improve/memory.py's M1/M2
skip a repository+pin whose coverage for the rule's language is only
`none` (counted under `coverage_none` in the proposal's excluded).

`ousast plane alerts-engine <Run.yaml> --source <frozen export>`
(plane/engine_alerts.py) does the alerts task on the host for cases whose
files include a language the engine covers but quick mode does not (PHP):
exports both pins from the case cache, runs the quick scan and the
openultrasast:dev engine container (finding_dump.py, --network none,
--memory 3g, one at a time, per-pin deadline), writes engine findings in
the alerts.jsonl row shape (rule_id engine:<family>, source engine,
in_fix_range from case.json) with a summary (files read, questions,
completed, seconds, degradations per pin), and marks the task done via
reconciler.mark_done. No result, no files read, or questions == 0 fails
loudly and leaves the run untouched. Refuses a git checkout as source.

Runner image rebuilt and re-pinned (sha256:ebb40a9a...); validation-46
regenerated (digest only). Live, recorded in
benchmarks/measurements/2026-09-30-php-engine-alerts/: froxlor 366 files,
130/130 questions per pin, 6 alerts per pin, 0 in the fix range; wp-gopay
19 files, 101/101 questions, 0 alerts. The loop: 32 run rows (coverage 8,
php=engine), 0 proposals, gate no_proposals, $0.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo

src/openultrasast/model/audit.py

@@ -66,6 +66,7 @@ SPEC_OWNED = {
     "plane.memory": "harnessx-removal Req 6.1/6.4: the memory store (file, MinIO), ingest and fact reuse; `ousast plane remember`",
     "plane.tasks.remember": "harnessx-removal Req 6.1: a case's delivered artifacts as memory rows, model-free",
     "plane.tasks.alerts": "harnessx-removal Req 6.3: quick-mode alerts on a case's vulnerable and fixed pins, model-free",
+    "plane.engine_alerts": "harnessx-removal Req 6.3: engine alerts where quick mode has no rules (PHP), on the host",
     "plane.tasks.loop": "harnessx-removal Req 6.3: the improvement loop's snapshot, measure, propose and improve steps",
     "plane.workspaces": "ai-service-plane task 4: Workspace manifests per case pin of a population; `ousast plane workspaces`",
     "plane.runner": "ai-service-plane Req 4.1-4.4: the ax-task-runner entrypoint (PID 1 of the task image); delivers the output directory",