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-protocol/src/protocol/v1.rs

@@ -596,34 +596,3 @@ impl InputItem {
         }
     }
 }
-
-#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
-#[serde(rename_all = "camelCase")]
-/// Deprecated in favor of AccountLoginCompletedNotification.
-pub struct LoginChatGptCompleteNotification {
-    #[schemars(with = "String")]
-    pub login_id: Uuid,
-    pub success: bool,
-    pub error: Option<String>,
-}
-
-#[derive(Serialize, Deserialize, Debug, Clone, JsonSchema, TS)]
-#[serde(rename_all = "camelCase")]
-pub struct SessionConfiguredNotification {
-    pub session_id: ThreadId,
-    pub model: String,
-    pub service_tier: Option<ServiceTier>,
-    pub reasoning_effort: Option<ReasoningEffort>,
-    pub history_log_id: u64,
-    #[ts(type = "number")]
-    pub history_entry_count: usize,
-    pub initial_messages: Option<Vec<EventMsg>>,
-    pub rollout_path: PathBuf,
-}
-
-#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
-#[serde(rename_all = "camelCase")]
-/// Deprecated notification. Use AccountUpdatedNotification instead.
-pub struct AuthStatusChangeNotification {
-    pub auth_method: Option<AuthMode>,
-}