Update codex to 0.115.0

[codex-acp-ci-app]

What's new

Previously failing tests and reasons:

• CodexAcpClient.test.ts → should authenticate with key: timed out waiting for auth completion, then failed snapshot due updated notification/model payload shape.
• CodexAcpClient.test.ts → should authenticate with a gateway: timed out initially; then failed with logout failed: Read-only file system.
• mcp-session.test.ts → should return configured mcp: timed out initially; then failed because /mcp reported no configured servers.
• Typecheck failure in CodexEventHandler.ts: non-exhaustive notification switch (Function lacks ending return statement).

What I changed and why:

• Updated auth flow in CodexAcpClient.ts so API-key login returns immediately when login is synchronous, avoiding indefinite waits meant for browser login flows.
• Replaced deprecated MCP startup waiting with MCP status lookup in CodexAcpClient.ts, and merged requested MCP names as fallback in CodexAcpServer.ts so session MCP visibility remains stable.
• Added explicit no-op handling for newly introduced notification variants in CodexEventHandler.ts to restore exhaustive typing.
• Hardened gateway auth test to use file-based credentials storage in sandboxed environments in CodexAcpClient.test.ts, preventing read-only keychain/logout failures.
• Updated the auth snapshot to reflect post-update protocol/model payloads in auth-with-key.json.
• Removed test debug logging noise in mcp-session.test.ts.

Repository metadata is currently on a read-only filesystem, so .git/index could not be written.