Move message history out of core (#21278)

## Why

Message history was implemented inside `codex-core` and surfaced through
core protocol ops and `SessionConfiguredEvent` fields even though the
current consumer is TUI-local prompt recall. That made core own UI
history persistence and exposed `history_log_id` / `history_entry_count`
through surfaces that app-server and other clients do not need.

This change moves message history persistence out of core and keeps the
recall plumbing local to the TUI.

## What changed

- Added a new `codex-message-history` crate for appending, looking up,
trimming, and reading metadata from `history.jsonl`.
- Removed core protocol history ops/events: `AddToHistory`,
`GetHistoryEntryRequest`, and `GetHistoryEntryResponse`.
- Removed `history_log_id` and `history_entry_count` from
`SessionConfiguredEvent` and updated exec/MCP/test fixtures accordingly.
- Updated the TUI to dispatch local app events for message-history
append/lookup and keep its persistent-history metadata in TUI session
state.

## Validation

- `cargo test -p codex-message-history -p codex-protocol`
- `cargo test -p codex-exec event_processor_with_json_output`
- `cargo test -p codex-mcp-server outgoing_message`
- `cargo test -p codex-tui`
- `just fix -p codex-message-history -p codex-protocol -p codex-core -p
codex-tui -p codex-exec -p codex-mcp-server`

codex-rs/exec/src/lib.rs

@@ -1153,8 +1153,6 @@ fn session_configured_from_thread_response(
         active_permission_profile,
         cwd,
         reasoning_effort,
-        history_log_id: 0,
-        history_entry_count: 0,
         initial_messages: None,
         network_proxy: None,
         rollout_path,

codex-rs/exec/tests/event_processor_with_json_output.rs

@@ -122,8 +122,6 @@ fn session_configured_produces_thread_started_event() {
         active_permission_profile: None,
         cwd: test_path_buf("/tmp/project").abs(),
         reasoning_effort: None,
-        history_log_id: 0,
-        history_entry_count: 0,
         initial_messages: None,
         network_proxy: None,
         rollout_path: None,