fix(codex): filter invalid generic item IDs

[moyuan10086]

Summary

• always emit a CLIProxyAPI payload filter for Codex Responses requests
• remove only direct input[*].id values matching the invalid generic item_* prefix
• preserve the existing Fast/priority service_tier payload default

This prevents resumed Codex conversations from failing with errors such as invalid_id_prefix when stored response items carry generic IDs that do not match their required typed prefixes (rs, fc, and others).

Fixes #1773

Validation

• cargo check -p cockpit-tools --tests passes
• added unit coverage for standard-speed payload generation
• added unit coverage for coexistence with the Fast/priority service-tier default
• git diff --check passes

On this Windows host, the compiled Rust test executable is currently blocked before the test harness starts by system loader error 0xc0000139 (STATUS_ENTRYPOINT_NOT_FOUND). The test target itself compiles successfully; CI can execute it in a clean runner.