app-server: Replay pending item requests on thread/resume (#12560)

Replay pending client requests after `thread/resume` and emit resolved
notifications when those requests clear so approval/input UI state stays
in sync after reconnects and across subscribed clients.

Affected RPCs:
- `item/commandExecution/requestApproval`
- `item/fileChange/requestApproval`
- `item/tool/requestUserInput`

Motivation:
- Resumed clients need to see pending approval/input requests that were
already outstanding before the reconnect.
- Clients also need an explicit signal when a pending request resolves
or is cleared so stale UI can be removed on turn start, completion, or
interruption.

Implementation notes:
- Use pending client requests from `OutgoingMessageSender` in order to
replay them after `thread/resume` attaches the connection, using
original request ids.
- Emit `serverRequest/resolved` when pending requests are answered
or cleared by lifecycle cleanup.
- Update the app-server protocol schema, generated TypeScript bindings,
and README docs for the replay/resolution flow.

High-level test plan:
- Added automated coverage for replaying pending command execution and
file change approval requests on `thread/resume`.
- Added automated coverage for resolved notifications in command
approval, file change approval, request_user_input, turn start, and turn
interrupt flows.
- Verified schema/docs updates in the relevant protocol and app-server
tests.

Manual testing:
- Tested reconnect/resume with multiple connections.
- Confirmed state stayed in sync between connections.

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

@@ -1422,6 +1422,32 @@
       ],
       "type": "object"
     },
+    "RequestId": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "format": "int64",
+          "type": "integer"
+        }
+      ]
+    },
+    "ServerRequestResolvedNotification": {
+      "properties": {
+        "requestId": {
+          "$ref": "#/definitions/RequestId"
+        },
+        "threadId": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "requestId",
+        "threadId"
+      ],
+      "type": "object"
+    },
     "SessionSource": {
       "oneOf": [
         {
@@ -3422,6 +3448,26 @@
       "title": "Item/fileChange/outputDeltaNotification",
       "type": "object"
     },
+    {
+      "properties": {
+        "method": {
+          "enum": [
+            "serverRequest/resolved"
+          ],
+          "title": "ServerRequest/resolvedNotificationMethod",
+          "type": "string"
+        },
+        "params": {
+          "$ref": "#/definitions/ServerRequestResolvedNotification"
+        }
+      },
+      "required": [
+        "method",
+        "params"
+      ],
+      "title": "ServerRequest/resolvedNotification",
+      "type": "object"
+    },
     {
       "properties": {
         "method": {