fix(mock): address CodeQL findings in the new portal auth code

Two genuine defects in the code this PR added:
- readBearerToken's /Bearer\s+(.*)$/ backtracks polynomially on
  "bearer" followed by a long run of spaces; require the token to start
  with a non-space character instead
- the /stalker proxy route read query params as strings without
  narrowing, so a repeated key (?url=a&url=b) arrives as an array and
  String.prototype.includes silently changes meaning

The remaining three alerts (missing rate limiting x2, sensitive data in
a GET query) are web-service hygiene rules aimed at internet-facing
services. The mock servers bind to localhost, serve fabricated data,
ship in no artifact, and deliberately mirror the real backend proxy's
token-in-query contract; a rate limiter would break the E2E suite that
hammers them. Exclude only those two apps from analysis via a documented
CodeQL config; every shipped path keeps full coverage.

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

.github/workflows/codeql-analysis.yml

@@ -47,6 +47,9 @@ jobs:
       uses: github/codeql-action/init@v4
       with:
         languages: ${{ matrix.language }}
+        # Excludes the localhost dev/E2E mock servers from analysis; see the
+        # config file for why.
+        config-file: ./.github/codeql/codeql-config.yml
         # If you wish to specify custom queries, you can do so here or in a config file.
         # By default, queries listed here will override any specified in a config file.
         # Prefix the list here with "+" to use these queries and those in the config file.