review: fix 26 findings from a 4-agent audit

CORRECTNESS
- lost-lease race: complete()/fail() did not check ownership, so a worker whose
  lease expired could mark a task done while another worker was running it, or
  requeue a task someone else owned. Reproduced, fixed with a CAS on
  (state, locked_by), pinned by two regression tests.
- worker died on report failure: _run_one's docstring claimed no exception
  escapes the TaskGroup; fail()/complete() were outside the guarded block, so a
  DB blip cancelled every sibling provision on the pod.
- claim query used an INNER join, which could strand a just-claimed task and
  report 'queue empty'. LEFT join.
- InstanceRepo.set_error bypassed the state machine and had no callers. Deleted.
- handle_deprovision ignored its CAS result, so a wrong-state instance kept a
  dangling endpoint and got re-provisioned by the drift check 60s later.
- handle_verify re-notified on every retry: five pages for one halt.

DEPLOY-BREAKING
- the migration Job could never succeed: no Dockerfile copied migrations/, and
  migrate.py resolved the path relative to the source tree, which only works for
  an editable install. Added COPY + SVCFORGE_MIGRATIONS_DIR.
- ServiceMonitor selector did not match the Service: API metrics never scraped.
- SvcforgeReconcilerStale fired permanently from every pod, because the gauge is
  module-level and every service exports it as 0. Scoped to the reconciler job.
- SvcforgeTaskFailed latched forever on a monotonic counter. Now increase()[15m].
- the digest guard accepted the all-zeros placeholder.
- worker terminationGracePeriodSeconds was 60s against a 600s helm timeout.

DEAD CODE THAT SHOULD NOT HAVE BEEN
- adapters/k8s.py was never called, so tenant namespaces were never created and
  the first provision for a new team would fail. Wired into handle_provision.
- adapters/redis.py was never imported by any service. Rate limiting is now wired
  into the API, failing open.
- Settings.check_production() had no callers. Given an explicit environment and
  called from every entrypoint.

OBSERVABILITY
- the API never called obs.setup(): no JSON logs, no trace correlation, log_json
  silently inert.
- LogNotifier's structured fields were discarded by the stdlib->structlog bridge.
- bind_task_context cleared the 'service' binding for the life of every task.
- split tasks_failed into task_attempts_failed and tasks_dead_lettered.

SECURITY
- trivy correctly blocked the worker/reconciler images: helm 3.16.2 and kubectl
  1.31.2 carry CRITICAL Go stdlib CVEs. Bumped to helm 3.21.3 and kubectl 1.35.3,
  which also closes a four-minor skew against the v1.35.3 cluster.

TESTS THAT COULD NOT FAIL
- the concurrency cap test passed on a fully serial worker.
- the alert/metric cross-check asserted a hardcoded list instead of reading the
  chart, so it could not catch a rename on the chart side.
- fixed OTel tracer-provider pollution between test files.

DOCS
- ARCHITECTURE.md: mermaid diagrams, user stories, and the helm-vs-ArgoCD
  guarantee (verified with --dry-run=server).
- AGENTS.md + CLAUDE.md.
- prose sweep for back-and-forth phrasing across 19 files.

services/worker/Dockerfile

@@ -41,8 +41,21 @@ RUN useradd -u 10001 -m -s /usr/sbin/nologin svcforge
 WORKDIR /app
 COPY --from=builder --chown=10001:10001 /app /app
 
-COPY --from=alpine/helm:3.16.2@sha256:a19a2968fd672336d39771f6c899781424d725229148656dbc2a1e305003cdec /usr/bin/helm /usr/local/bin/helm
-COPY --from=bitnamilegacy/kubectl:1.31.2@sha256:0eab9ec8f5e0f75271277467ebb7513b36dea0122bc68615d18c47fece4fd82c /opt/bitnami/kubectl/bin/kubectl /usr/local/bin/kubectl
+# helm 3.21.3, not 3.16.2. 3.16.2 was built with Go 1.22.9 and carries CRITICAL
+# CVE-2025-68121 (crypto/tls) and CVE-2026-33186 (grpc), plus HIGH CVE-2026-35469
+# (spdystream, fixed in 0.5.1) — trivy fails the build on them and is right to.
+# Deliberately 3.x: helm 4 is a breaking change and is not a CVE fix.
+COPY --from=alpine/helm:3.21.3@sha256:35da09ba0716fc7c3cd63b6b31ee380a9c7662e95f29ab0e4ae962420afd315b /usr/bin/helm /usr/local/bin/helm
+# kubectl 1.35.3 from the OFFICIAL registry.k8s.io image, replacing
+# bitnamilegacy/kubectl:1.31.2. Two reasons, either sufficient:
+#   - CVEs: the bitnami image is Go 1.22.9 and ships containerd < 1.7.29 (HIGH
+#     CVE-2024-25621) along with the same crypto/tls and grpc CRITICALs as helm above.
+#   - Skew: the target cluster runs v1.35.3. 1.31.2 is four minors behind, well outside
+#     kubectl's supported +/-1 window, so it was unsupported against this cluster.
+# bitnamilegacy publishes no 1.35 tag. registry.k8s.io/kubectl is the upstream-maintained
+# image, is a manifest list with linux/arm64 (this cluster is Ampere), and puts the binary
+# at /bin/kubectl rather than bitnami's /opt/bitnami path.
+COPY --from=registry.k8s.io/kubectl:v1.35.3@sha256:8dad99b604a2c0bafe17f53cadf78482d6f667a6da687f385508f5f4e4696d37 /bin/kubectl /usr/local/bin/kubectl
 
 ENV PATH="/app/.venv/bin:$PATH" \
     PYTHONUNBUFFERED=1 \