chore(app-server): delete v1 RPC methods and notifications (#13375)

## Summary
This removes the old app-server v1 methods and notifications we no
longer need, while keeping the small set the main codex app client still
depends on for now.

The remaining legacy surface is:
- `initialize`
- `getConversationSummary`
- `getAuthStatus`
- `gitDiffToRemote`
- `fuzzyFileSearch`
- `fuzzyFileSearch/sessionStart`
- `fuzzyFileSearch/sessionUpdate`
- `fuzzyFileSearch/sessionStop`

And the raw `codex/event/*` notifications emitted from core. These
notifications will be removed in a followup PR.

## What changed
- removed deprecated v1 request variants from the protocol and
app-server dispatcher
- removed deprecated typed notifications: `authStatusChange`,
`loginChatGptComplete`, and `sessionConfigured`
- updated the app-server test client to use v2 flows instead of deleted
v1 flows
- deleted legacy-only app-server test suites and added focused coverage
for `getConversationSummary`
- regenerated app-server schema fixtures and updated the MCP interface
docs to match the remaining compatibility surface

## Testing
- `just write-app-server-schema`
- `cargo test -p codex-app-server-protocol`
- `cargo test -p codex-app-server`

codex-rs/app-server/tests/suite/auth.rs

@@ -6,8 +6,7 @@ use codex_app_server_protocol::GetAuthStatusParams;
 use codex_app_server_protocol::GetAuthStatusResponse;
 use codex_app_server_protocol::JSONRPCError;
 use codex_app_server_protocol::JSONRPCResponse;
-use codex_app_server_protocol::LoginApiKeyParams;
-use codex_app_server_protocol::LoginApiKeyResponse;
+use codex_app_server_protocol::LoginAccountResponse;
 use codex_app_server_protocol::RequestId;
 use pretty_assertions::assert_eq;
 use std::path::Path;
@@ -72,18 +71,15 @@ forced_login_method = "{forced_method}"
 }
 
 async fn login_with_api_key_via_request(mcp: &mut McpProcess, api_key: &str) -> Result<()> {
-    let request_id = mcp
-        .send_login_api_key_request(LoginApiKeyParams {
-            api_key: api_key.to_string(),
-        })
-        .await?;
+    let request_id = mcp.send_login_account_api_key_request(api_key).await?;
 
     let resp: JSONRPCResponse = timeout(
         DEFAULT_READ_TIMEOUT,
         mcp.read_stream_until_response_message(RequestId::Integer(request_id)),
     )
     .await??;
-    let _: LoginApiKeyResponse = to_response(resp)?;
+    let response: LoginAccountResponse = to_response(resp)?;
+    assert_eq!(response, LoginAccountResponse::ApiKey {});
     Ok(())
 }
 
@@ -211,9 +207,7 @@ async fn login_api_key_rejected_when_forced_chatgpt() -> Result<()> {
     timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
 
     let request_id = mcp
-        .send_login_api_key_request(LoginApiKeyParams {
-            api_key: "sk-test-key".to_string(),
-        })
+        .send_login_account_api_key_request("sk-test-key")
         .await?;
 
     let err: JSONRPCError = timeout(