refactor(crdt): implement proxy-resilient Yjs dual-transport sync with indexeddb offline-first and debounced sqlite persistence

frontend/package-lock.json

@@ -14,6 +14,7 @@
         "prismjs": "^1.30.0",
         "react": "^18.3.1",
         "react-dom": "^18.3.1",
+        "y-indexeddb": "^9.0.12",
         "yjs": "^13.6.33"
       },
       "devDependencies": {
@@ -2782,6 +2783,26 @@
         }
       }
     },
+    "node_modules/y-indexeddb": {
+      "version": "9.0.12",
+      "resolved": "https://registry.npmjs.org/y-indexeddb/-/y-indexeddb-9.0.12.tgz",
+      "integrity": "sha512-9oCFRSPPzBK7/w5vOkJBaVCQZKHXB/v6SIT+WYhnJxlEC61juqG0hBrAf+y3gmSMLFLwICNH9nQ53uscuse6Hg==",
+      "license": "MIT",
+      "dependencies": {
+        "lib0": "^0.2.74"
+      },
+      "engines": {
+        "node": ">=16.0.0",
+        "npm": ">=8.0.0"
+      },
+      "funding": {
+        "type": "GitHub Sponsors ❤",
+        "url": "https://github.com/sponsors/dmonad"
+      },
+      "peerDependencies": {
+        "yjs": "^13.0.0"
+      }
+    },
     "node_modules/yallist": {
       "version": "3.1.1",
       "resolved": "https://registry.npmjs.org/yallist/-/yallist-3.1.1.tgz",