## Why
This is another straight-refactor step in the `codex-tools` migration.
`core/src/tools/handlers/tool_suggest.rs` still owned request/response
payload structs, elicitation metadata shaping, and connector-completion
predicates that do not depend on `codex-core` session/runtime internals.
Per the `AGENTS.md` guidance to keep shrinking `codex-core`, this moves
that pure wire-format logic into `codex-rs/tools` so the core handler
keeps only session orchestration, plugin/config refresh, and MCP cache
updates.
## What changed
- Added `codex-rs/tools/src/tool_suggest.rs` and exported its API from
`codex-rs/tools/src/lib.rs`.
- Moved `ToolSuggestArgs`, `ToolSuggestResult`, `ToolSuggestMeta`,
`build_tool_suggestion_elicitation_request()`,
`all_suggested_connectors_picked_up()`, and
`verified_connector_suggestion_completed()` into `codex-tools`.
- Rewired `core/src/tools/handlers/tool_suggest.rs` to consume those
exports directly.
- Ported the existing pure helper tests from
`core/src/tools/handlers/tool_suggest_tests.rs` to
`tools/src/tool_suggest_tests.rs` without adding new behavior coverage.
## Validation
```shell
cargo test -p codex-tools
cargo test -p codex-core tools::handlers::tool_suggest::tests
just argument-comment-lint
```
