ci: retry CodeQL init on transient bundle-download ECONNRESET

The CodeQL Analyze Python job failed on the #757 merge commit with
ECONNRESET while streaming the CodeQL bundle download in
codeql-action/init's "Setup CodeQL tools" step. This is unrelated to
the merged code — it's a known, currently-unaddressed gap in
codeql-action: the download error is retryable but the action doesn't
retry it internally (confirmed via codeql-action's issue tracker and
changelog).

Since a `uses:` step can't be wrapped by a shell-level retry action,
Initialize CodeQL now runs up to 3 times, cascading to the next
attempt only if the previous one failed, so the common case (success
on attempt 1) costs nothing extra.

.github/workflows/codeql.yml

@@ -22,7 +22,36 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v7
 
-      - name: Initialize CodeQL
+      # The CodeQL bundle download (github/codeql-action/init's "Setup CodeQL
+      # tools" step) streams a ~1GB tarball from GitHub's release CDN and
+      # does not retry on a transient connection reset (ECONNRESET) itself
+      # (github/codeql-action, unresolved as of v4 / CLI 2.26.1: the HTTP
+      # error is retryable but isn't retried internally). Since a `uses:`
+      # step can't be wrapped by a shell-level retry action, attempt init
+      # up to 3 times; each retry is a fresh download attempt with no
+      # meaningful state carried over from a failed attempt.
+      - name: Initialize CodeQL (attempt 1)
+        id: codeql-init-1
+        uses: github/codeql-action/init@v4
+        continue-on-error: true
+        with:
+          languages: python
+          queries: security-and-quality
+          config-file: .github/codeql/codeql-config.yml
+
+      - name: Initialize CodeQL (attempt 2)
+        id: codeql-init-2
+        if: steps.codeql-init-1.outcome == 'failure'
+        uses: github/codeql-action/init@v4
+        continue-on-error: true
+        with:
+          languages: python
+          queries: security-and-quality
+          config-file: .github/codeql/codeql-config.yml
+
+      - name: Initialize CodeQL (attempt 3)
+        id: codeql-init-3
+        if: steps.codeql-init-2.outcome == 'failure'
         uses: github/codeql-action/init@v4
         with:
           languages: python