feat(page-data): add private and public dataset API (phase 1-3)

Extract UserDataSpaceService for shared SQLite access, wire logged-in Page
Data routes, and add public insert plus password-token read/update/delete with
policy storage, rate limits, and regression tests.

Co-authored-by: Cursor <cursoragent@cursor.com>

scripts/run-memind-tests.mjs

@@ -132,6 +132,18 @@ const SCOPE_RULES = [
       'plaza-ops.test.mjs',
     ],
   },
+  {
+    id: 'page-data',
+    patterns: [/page-data/i, /page-access-policy/i, /user-data-space-service/i, /mindspace-sandbox-mcp/i],
+    tests: [
+      'user-data-space-service.test.mjs',
+      'page-access-policy.test.mjs',
+      'page-data-routes.test.mjs',
+      'page-data-public-service.test.mjs',
+      'page-data-integration.test.mjs',
+      'mindspace-sandbox-mcp.test.mjs',
+    ],
+  },
   {
     id: 'mindspace-core',
     patterns: [/mindspace/i, /server\.mjs$/, /src\/hooks\/useTKMind/i],