Run the desktop's model layer in the browser

The browser host now stores data through yaak-models compiled to wasm — the
same queries, migrations, cascade rules, duplicate naming and first-run
bootstrap the desktop and CLI use — instead of a TypeScript port of them.

- crates/yaak-web: the wasm crate. boot() registers an IndexedDB-backed VFS
  and calls init_standalone; rpc(cmd, payload, label) answers the models_*
  commands via ClientDb and returns the model_writes it caused; blob get/put
  through blob_manager. Built like yaak-templates (pkg/ committed); the
  build script keeps pkg/ and says so when no wasm-capable clang is present,
  so a desktop bootstrap never depends on one.
- models_ops moves from crates/yaak into yaak-models so the wasm crate can
  use it without the send engine.
- The database lives in a SharedWorker (packages/platform/src/web/worker.ts):
  one process holds the data and pushes writes to every tab, as on the
  desktop. Where SharedWorker is missing or its script cannot be fetched, a
  dedicated worker guarded by a Web Lock takes over and a second tab is told
  so. The worker imports the wasm lazily so a tab's connect is answered
  instantly; the tab reconnects if it isn't.
- packages/platform/src/web loses models.ts, schema.ts, db.ts and the
  BroadcastChannel; commands.ts forwards model commands to the worker and
  keeps the fixed answers and refusals.

Verified in Chrome, dev and production builds: bootstrap, CRUD across every
model type, serde defaults, engine-format ids, Rust copy naming, folder
cascade with per-descendant events, single-event workspace delete, reload
persistence, two tabs coherent, Send declined with a toast, 8/8 reloads
rendering in ~100 ms.

package-lock.json

@@ -59,6 +59,7 @@
         "crates-tauri/yaak-fonts",
         "crates-tauri/yaak-license",
         "crates-tauri/yaak-mac-window",
+        "crates/common/yaak-rpc-schema",
         "crates/yaak-crypto",
         "crates/yaak-git",
         "crates/yaak-models",
@@ -66,6 +67,7 @@
         "crates/yaak-sse",
         "crates/yaak-sync",
         "crates/yaak-templates",
+        "crates/yaak-web",
         "crates/yaak-ws",
         "crates-proxy/yaak-proxy-lib",
         "apps/yaak-client",
@@ -290,6 +292,10 @@
       "name": "@yaakapp-internal/mac-window",
       "version": "1.0.0"
     },
+    "crates/common/yaak-rpc-schema": {
+      "name": "@yaakapp-internal/rpc-schema",
+      "version": "1.0.0"
+    },
     "crates/yaak-crypto": {
       "name": "@yaakapp-internal/crypto",
       "version": "1.0.0"
@@ -324,6 +330,13 @@
         "rimraf": "^6.1.2"
       }
     },
+    "crates/yaak-web": {
+      "name": "@yaakapp-internal/web",
+      "version": "1.0.0",
+      "devDependencies": {
+        "rimraf": "^6.1.2"
+      }
+    },
     "crates/yaak-ws": {
       "name": "@yaakapp-internal/ws",
       "version": "1.0.0"
@@ -5753,6 +5766,10 @@
       "resolved": "crates-proxy/yaak-proxy-lib",
       "link": true
     },
+    "node_modules/@yaakapp-internal/rpc-schema": {
+      "resolved": "crates/common/yaak-rpc-schema",
+      "link": true
+    },
     "node_modules/@yaakapp-internal/sse": {
       "resolved": "crates/yaak-sse",
       "link": true
@@ -5785,6 +5802,10 @@
       "resolved": "packages/ui",
       "link": true
     },
+    "node_modules/@yaakapp-internal/web": {
+      "resolved": "crates/yaak-web",
+      "link": true
+    },
     "node_modules/@yaakapp-internal/ws": {
       "resolved": "crates/yaak-ws",
       "link": true
@@ -17189,7 +17210,8 @@
         "@tauri-apps/plugin-dialog": "^2.7.1",
         "@tauri-apps/plugin-fs": "^2.5.1",
         "@tauri-apps/plugin-opener": "^2.5.4",
-        "@tauri-apps/plugin-os": "^2.3.2"
+        "@tauri-apps/plugin-os": "^2.3.2",
+        "@yaakapp-internal/rpc-schema": "^1.0.0"
       }
     },
     "packages/plugin-runtime": {