ci: cancel superseded PR runs and make the bandit job a real gate (#231)

* ci: cancel superseded PR runs and make the bandit job a real gate

No PR workflow had a concurrency group, so a new push left the previous
run occupying 16 Python matrix runners, the real ComfyUI job and the
three viewerjs jobs for up to 25 minutes. Add a group per workflow and
PR ref that cancels the older run. Pushes to main use the run id as
their group, so no main commit is ever cancelled or dropped as pending.

Remove the lint job from code-quality.yml. It ran black and flake8 a
second time, partly with --exit-zero, next to the protected "black and
flake8" job in test.yml.

The security job ran bandit with "|| true" and could never fail. At
medium severity it reports 74 findings today, so it now gates on high
severity only and prints the medium report without failing. The only
two high findings were SHA1 and MD5 used as a gallery entry id and a
LoRA preview cache filename; mark both usedforsecurity=False, which
leaves every hash value unchanged.

Closes #230.

* ci: verify superseded PR runs are cancelled

* ci: require the bandit high-severity check

Review on #231 pointed out that a failing bandit job did not block a
merge because its context was not required. Name the job
"bandit (high severity)" so the required context is unambiguous, and
add it to .github/branch-protection.json and the TESTING.md list of
required checks.

.github/workflows/code-quality.yml

@@ -9,42 +9,15 @@ on:
   pull_request:
     branches: [main]
 
+# Superseded PR pushes cancel their older run. Every main push gets its own
+# group (run_id), so no main commit's run is ever cancelled or dropped as pending.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event_name == 'pull_request' && github.ref || github.run_id }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
 jobs:
-  lint:
-    runs-on: ubuntu-latest
-
-    steps:
-      - uses: actions/checkout@v7
-
-      - name: Set up Python 3.10
-        uses: actions/setup-python@v7
-        with:
-          python-version: "3.10"
-
-      - name: Cache pip dependencies
-        uses: actions/cache@v6
-        with:
-          path: ~/.cache/pip
-          key: ${{ runner.os }}-pip-quality-${{ hashFiles('requirements-dev.txt') }}
-          restore-keys: |
-            ${{ runner.os }}-pip-quality-
-
-      - name: Install dependencies
-        run: |
-          python -m pip install --upgrade pip
-          pip install -r requirements-dev.txt
-
-      - name: Check formatting with Black
-        run: black --check --diff .
-
-      - name: Lint with flake8
-        run: |
-          # Fail on syntax errors and undefined names
-          flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
-          # Warnings as non-blocking
-          flake8 . --count --exit-zero --max-line-length=88 --statistics --exclude=reference/,.git,__pycache__,web/
-
   security:
+    name: bandit (high severity)
     runs-on: ubuntu-latest
 
     steps:
@@ -58,5 +31,9 @@ jobs:
       - name: Install bandit
         run: pip install bandit[toml]
 
-      - name: Security scan
-        run: bandit -r . -ll --exclude=./tests,./reference,./venv -q || true
+      # Medium findings are reported without failing until they are triaged.
+      # High severity is a hard gate.
+      - name: Security report (medium and above, informational)
+        run: bandit -r . -ll -q --exclude ./tests,./reference,./venv,./tools/vendor/node_modules --exit-zero
+      - name: Security scan (high severity gate)
+        run: bandit -r . -lll -q --exclude ./tests,./reference,./venv,./tools/vendor/node_modules