Merge pysim-otaman-server into otaman (monorepo, v1.7.0)

- Move PWA into frontend/; server package at pysim_otaman_server/
- Server now serves the PWA (same origin -> no CORS/PNA): static file handler
  + --web-dir flag + injects window.PYSIM_EMBEDDED marker into index.html
- Frontend defaults to relative API base when embedded (pysimBase = '')
- Version 1.7.0 aligned: server.py VERSION, pyproject.toml, PWA header
- SW cache bump otaman-v7 -> otaman-v8
- Docs: combined README + docs/api.md endpoint reference; update links
- Fix stale package.json repository URL

.gitignore

@@ -1 +1,6 @@
 node_modules/
+.venv/
+__pycache__/
+*.egg-info/
+dist/
+build/