feat(acp): route session/setTitle to the new schema types

[daniel-agentee]

Summary

Wires the SetSessionTitleRequest / SetSessionTitleResponse types into the agent-side JSON-RPC dispatch tables, so ACP-backed agents can implement Agent::set_session_title and have it dispatched here.

Why

This is the Rust SDK half of session/setTitle. Once the schema crate ships a release containing those types, this routing makes them callable.

What's in this PR

• src/agent-client-protocol/src/schema/client_to_agent/requests.rs — adds SetSessionTitleRequest/SetSessionTitleResponse to the imports and registers them with impl_jsonrpc_request! against "session/setTitle".
• src/agent-client-protocol/src/schema/enum_impls.rs — adds SetSessionTitleRequest to the ClientRequest enum dispatch so the agent-side connection knows to deserialize it as a setTitle request.

Total: 7 added lines, 2 files.

Stacking + CI status

Draft. CI is currently red because the types SetSessionTitleRequest / SetSessionTitleResponse do not yet exist in any released agent-client-protocol-schema version on crates.io — they live behind agentclientprotocol/agent-client-protocol#1199. Once that schema PR merges and a release ships (likely agent-client-protocol-schema = 0.14.0), bump the workspace dep here from =0.13.0 to the new version and CI will go green with no other changes.

Verified locally against the patched schema crate (cargo build / cargo test --all-features --workspace), all 51 tests pass.

Companion PRs

• Schema: Add session/setTitle method agent-client-protocol#1199 (must merge + release first)
• Agent reference impl: Handle session/setTitle and emit SessionInfoUpdate zed-industries/codex-acp#286 (uses this routing via [patch.crates-io] until the release lands)

[daniel-agentee]

Updated this branch for the current schema PR: bumped agent-client-protocol-schema to =0.13.5, added a temporary patch to agentclientprotocol/agent-client-protocol#1199, and removed the stale session/set_model routing/feature path that the current schema has dropped. Local validation is green: cargo fmt --all -- --check, cargo clippy --all-targets --all-features -- -D warnings, cargo build -p agent-client-protocol-test --bin testy --all-features, cargo test --all-features, and git diff --check.

@codex review

[daniel-agentee]

@codex review

[daniel-agentee]

Refreshed this branch onto current main in 79bb427 and kept the temporary schema patch pointed at agentclientprotocol/agent-client-protocol#1199 (df5ce77) so the new SetSessionTitle* types are resolvable before release. Local validation is green: cargo fmt --all -- --check, cargo clippy --all-targets --all-features -- -D warnings, cargo build -p agent-client-protocol-test --bin testy --all-features, cargo test --all-features, and git diff --check. I also left the older 0.11-compatible routing rev reachable on daniel-agentee/session-set-title-0.11-compat for zed-industries/codex-acp#286 while it still depends on agent-client-protocol = 0.11.1.

[daniel-agentee]

@codex review