fix(ci): triage semgrep findings, make the gate blocking (WP-30 #6)

Local semgrep run found 25 findings (not the WP's remembered 27 — already-stale
by the time this ran): dependabot cooldown, npm min-release-age, every GitHub
Action pinned to a full commit SHA (dependabot's existing github-actions
ecosystem entry keeps these current), and 2 detect-non-literal-regexp findings
in e2e/create-ssp.mjs suppressed as false positives (non-attacker-controlled
input: a test's own captured version number, a local generator's CLI arg).
`semgrep scan` now runs with `--error`, a real blocking gate instead of
report-only.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -20,8 +20,8 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 15
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 24
           cache: npm
@@ -62,15 +62,15 @@ jobs:
       options: --cpus=2 --memory=4g --memory-swap=4g
     timeout-minutes: 15
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 24
           cache: npm
       - run: npm ci --prefer-offline --no-audit --no-fund
       # Cache the chromium download across runs; `install --with-deps` then only
       # runs the (fast, idempotent) apt deps check on a hit.
-      - uses: actions/cache@v4
+      - uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
           path: ~/.cache/ms-playwright
           key: playwright-${{ runner.os }}-${{ hashFiles('package-lock.json') }}
@@ -82,11 +82,11 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 15
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-dotnet@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+      - uses: actions/setup-dotnet@67a3573c9a986a3f9c594539f4ab511d57bb3ce9 # v4.3.1
         with:
           dotnet-version: 10.0.x
-      - uses: actions/cache@v4
+      - uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
           path: ~/.nuget/packages
           key: nuget-${{ runner.os }}-${{ hashFiles('**/*.csproj') }}
@@ -109,21 +109,21 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 15
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 24
           cache: npm
-      - uses: actions/setup-dotnet@v4
+      - uses: actions/setup-dotnet@67a3573c9a986a3f9c594539f4ab511d57bb3ce9 # v4.3.1
         with:
           dotnet-version: 10.0.x
-      - uses: actions/cache@v4
+      - uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
           path: ~/.nuget/packages
           key: nuget-${{ runner.os }}-${{ hashFiles('**/*.csproj') }}
           restore-keys: nuget-${{ runner.os }}-
       - run: npm ci --prefer-offline --no-audit --no-fund
-      - uses: actions/cache@v4
+      - uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
           path: ~/.cache/ms-playwright
           key: playwright-${{ runner.os }}-${{ hashFiles('package-lock.json') }}
@@ -141,35 +141,36 @@ jobs:
     # semgrep's deps (e.g. PyJWT) are already present as apt-managed packages, which pip cannot
     # uninstall ("RECORD file not found") — this flag installs fresh without uninstalling, so it
     # never touches the Debian copies. Don't drop it.
-    # ponytail: report-only for now (no `--error`, so the job stays green while the initial
-    # findings are triaged); flip to `--error` to make it a blocking gate. See WP-30.
+    # WP-30: initial findings triaged (dependabot cooldown, npm min-release-age, GH Actions
+    # pinned to SHA, 2 nosemgrep'd ReDoS false positives on non-attacker-controlled input) —
+    # `--error` below makes this a real blocking gate, not report-only.
     runs-on: ubuntu-latest
     timeout-minutes: 15
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
       - run: python3 -m pip install --break-system-packages --ignore-installed semgrep
       # p/default = curated cross-language security (covers JS/TS); p/csharp = the backend.
       # Anonymous registry fetch; --metrics=off disables telemetry (not `auto`, which uploads
       # project metadata).
-      - run: semgrep scan --config p/default --config p/csharp --metrics=off
+      - run: semgrep scan --config p/default --config p/csharp --metrics=off --error
 
   api-client-drift:
     # The committed typed client must match the backend OpenAPI doc.
     runs-on: ubuntu-latest
     timeout-minutes: 15
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 24
           cache: npm
-      - uses: actions/setup-dotnet@v4
+      - uses: actions/setup-dotnet@67a3573c9a986a3f9c594539f4ab511d57bb3ce9 # v4.3.1
         with:
           # 8.0 for the bundled NSwag runtime, 10.0 to build/emit the spec.
           dotnet-version: |
             8.0.x
             10.0.x
-      - uses: actions/cache@v4
+      - uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
           path: ~/.nuget/packages
           key: nuget-${{ runner.os }}-${{ hashFiles('**/*.csproj') }}