fix(security): remediate 2026-05-12 audit findings (Stages 2–5)

Remediation of the 2026-05-12/13 audits (78 findings + cluster gaps),
tracked in deploy-k3s/SECURITY.md, plus fixes from two independent
post-remediation reviews.

Auth & sessions:
- SHA-256 hashed auth-token storage (C1); prior-token cache eviction on
  re-login (MEDIUM-1)
- local Google JWKS verification, iss/aud/exp checks (C2/C3)
- constant-time login + generic errors (L1/LIVE-L11/LIVE-L13)
- per-account login lockout keyed on distinct source IPs (M5/MEDIUM-3)
- verified-email gating, login rate limiting (LIVE-L19, H1-H3)

IAP & webhooks:
- Apple/Google cross-account replay protection (C5/C6/C10/C13, H5/H6)
- migrations 000003-000006 (token hashing, IAP replay, audit_log +
  webhook_event_log table creation, append-only audit log)

Authorization & races:
- file-ownership owner-OR-member fix (C7), atomic share-code join
  (C9/H9), device-token reassignment (C8/LOW-3)

Secrets & deploy:
- secrets file-mounted at /etc/honeydue/secrets, not env (F8); Redis
  password out of the ConfigMap (HIGH-1); B2 keys reconciled
- digest-pinned images, admin ingress hardening, CSP/HSTS, /metrics
  lockdown; kubeconfig 0600, etcd secrets-encryption, fail2ban +
  unattended-upgrades at provision; secret-rotation runbook

Build, vet, and the full test suite (incl. -race) pass; the goose
migration chain is verified against PostgreSQL 16.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

deploy-k3s/manifests/redis/deployment.yaml

@@ -20,6 +20,9 @@ spec:
         app.kubernetes.io/part-of: honeydue
     spec:
       serviceAccountName: redis
+      # Explicit pod-level opt-out (audit F11) — defense-in-depth on top of
+      # the ServiceAccount-level setting in rbac.yaml.
+      automountServiceAccountToken: false
       nodeSelector:
         honeydue/redis: "true"
       securityContext:
@@ -31,7 +34,9 @@ spec:
           type: RuntimeDefault
       containers:
         - name: redis
-          image: redis:7-alpine
+          # Pinned by digest (audit K3S-F14) — redis:7-alpine is 7.4.9-alpine.
+          image: redis:7-alpine@sha256:6ab0b6e7381779332f97b8ca76193e45b0756f38d4c0dcda72dbb3c32061ab99
+          imagePullPolicy: IfNotPresent  # audit CODE-L4 — explicit
           command:
             - sh
             - -c