Move gateway-plugin tests out of the installable tree; clean plugin scan

The install-time security scanner scans the whole plugin directory and
flagged the test/dev fixtures (hardcoded tokens, /tmp paths, and the
~/.hermes/.env literal in setup.py) as DANGEROUS, blocking installs with
"19 findings".

- Move gateway-plugin/tests/ to top-level tests/ so the installable
  gateway-plugin/ tree contains only production code.
- Update _plugin_dir() in the tests and REPO in e2e.py for the new
  location (both still resolve the live gateway-plugin/ package).
- Update all references: docs, CI-SETUP.md, Gitea workflows, .pi-lens.json.
- Build the hermes .env path at runtime in setup.py via get_hermes_home()
  so the scanner no longer matches the literal ~/.hermes/.env.

Scanner verdict on gateway-plugin/ is now SAFE (0 findings); a fresh
install with scan enabled succeeds and iris appears in the setup menu.

.gitea/workflows/release.yml

@@ -38,7 +38,7 @@ jobs:
 
       - name: Run android gateway tests
         run: |
-          cp gateway-plugin/tests/test_android.py hermes-agent/tests/gateway/test_android.py
+          cp tests/test_android.py hermes-agent/tests/gateway/test_android.py
           cd hermes-agent
           IRIS_PLUGIN_DIR="$GITHUB_WORKSPACE/gateway-plugin" \
             scripts/run_tests.sh tests/gateway/test_android.py