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

frontend/tests/html.test.js

@@ -0,0 +1,12 @@
+const { test } = require('node:test');
+const assert = require('node:assert');
+const fs = require('node:fs');
+const path = require('node:path');
+
+const html = fs.readFileSync(path.join(__dirname, '..', 'index.html'), 'utf8');
+const opens = (html.match(/<div\b/g) || []).length;
+const closes = (html.match(/<\/div>/g) || []).length;
+
+test('HTML <div> tags are balanced', () => {
+    assert.strictEqual(opens, closes, `Unbalanced divs: ${opens} opens vs ${closes} closes`);
+});