Vendor app-server protocol schema fixtures

Motivation:
- Keep `codex app-server` protocol artifacts (TypeScript + JSON Schema) checked in for consumers (e.g. IDE integrations) and make changes reviewable.
- Prevent drift between generated output (`codex app-server generate-ts` / `codex app-server generate-json-schema`) and what is vendored in the repo.

What changed:
- Vendor generated artifacts under `codex-rs/app-server-protocol/schema/typescript/` and `codex-rs/app-server-protocol/schema/json/`.
- Add `just write-app-server-schema` to fully regenerate fixtures (including deleting stale files).
- Add a fixture sync test for `codex-app-server-protocol` to assert the vendored trees match freshly generated output.
- Canonicalize JSON schema output (sorted object keys) for deterministic diffs.
- Wire Bazel test data so remote tests can read the vendored fixtures.

Refs: openai/codex#8956 (config.schema.json vendoring + sync test pattern)

codex-rs/app-server-protocol/schema/json/ClientNotification.json

@@ -0,0 +1,22 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "oneOf": [
+    {
+      "properties": {
+        "method": {
+          "enum": [
+            "initialized"
+          ],
+          "title": "InitializedNotificationMethod",
+          "type": "string"
+        }
+      },
+      "required": [
+        "method"
+      ],
+      "title": "InitializedNotification",
+      "type": "object"
+    }
+  ],
+  "title": "ClientNotification"
+}