chore(ci): unblock the CVE gate, finish Sonnet 5, parallelize, harden the supply chain (#1223)

Unblocks docker-image-scan (red 5 runs straight on GHSA-f88m-g3jw-g9cj: next's nested sharp@0.34.5, deduped via an override).

Finishes the #1218 Sonnet 5 rollout: compliance-pr and compliance-swarm were falling through to compliancemaxx's sonnet-4-6 default; swedish-compliance-review.mjs budgeted max_tokens as if thinking were off (it is adaptive-by-default on Sonnet 5) and never checked stop_reason; pr-agent's token budgets were sized for 4.6's tokenizer and its hidden default OpenAI fallback list is now emptied explicitly.

Core build 7m43s -> 2m51s measured (parallel checks/build/test, unit suite sharded 4 ways). Docker publish moves off QEMU to native ARM runners with a digest-merge job, so tags apply only on success and latest never moves on failure.

40 actions pinned to immutable SHAs; adds zizmor (0 high after fixing persist-credentials on 7 checkouts and permissions on test-pg-real) and CodeQL (0 findings on first run).

Full details in the PR body.

.github/workflows/swedish-compliance-diff.yml

@@ -19,7 +19,7 @@ jobs:
   prepare:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           ref: ${{ github.event.pull_request.head.sha }}
           fetch-depth: 0
@@ -41,7 +41,7 @@ jobs:
           git diff --name-only "$MERGE_BASE" HEAD > files.txt
           printf '%s\n' "$PR_NUMBER" > pr-number.txt
       - name: Upload diff artifact
-        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: compliance-input
           path: |