Merge simtrace-analyser PWA into frontend/ (monorepo); serve it same-origin

- frontend/: simtrace-analyser PWA (index.html, sw.js, manifest.json,
  icons, tests/index.test.html) copied in fresh
- server.py: static file serving (_STATIC_MIME, _serve_static) with
  path-traversal guard; injects window.SIMTRACE_EMBEDDED='1' into
  index.html so the PWA defaults to a relative API base
- server __main__: --web-dir (default <repo>/frontend)
- frontend: embedded same-origin mode; sw.js relative precache paths +
  cache v4; GitHub link + version-warn point at simtrace2-pysniff
- version 1.1.0 everywhere (__version__, pyproject, PWA_VERSION,
  manifest); MIN_SERVER_VERSION stays 1.0.0
- README/scripts/.gitignore updated

Tests: 107.

server-start.sh

@@ -72,4 +72,5 @@ ARGS+=(--port "$PORT")
 ARGS+=("${EXTRA_ARGS[@]}")
 
 echo "Starting simtrace2-pysniff-server..." >&2
+echo "PWA (simtrace-analyser) will be served at http://127.0.0.1:$PORT/" >&2
 exec env PYTHONPATH="$PROJECT_DIR" python3 -m simtrace2_pysniff.server "${ARGS[@]}"