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/mod.rs

@@ -1,16 +1,4 @@
-mod archive_thread;
 mod auth;
-mod codex_message_processor_flow;
-mod config;
-mod create_thread;
-mod fork_thread;
+mod conversation_summary;
 mod fuzzy_file_search;
-mod interrupt;
-mod list_resume;
-mod login;
-mod output_schema;
-mod send_message;
-mod set_default_model;
-mod user_agent;
-mod user_info;
 mod v2;