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.

tests/test_pcap_import.py

@@ -140,7 +140,7 @@ class TestImportEndpoint(unittest.TestCase):
 class TestVersion(unittest.TestCase):
     def test_package_version(self):
         from simtrace2_pysniff import __version__
-        self.assertEqual(__version__, '1.0.0')
+        self.assertEqual(__version__, '1.1.0')
 
     def test_status_includes_version(self):
         import os