feat: route aggregate providers by model

[kokotao]

Summary

• add aggregate provider model route rules with wildcard matching and priority ordering
• route matching selects the target member provider before fallback strategy is used
• rewrite proxied upstream model to the selected member provider default model in aggregate mode
• write aggregate Codex provider config with requires_openai_auth = false
• add manager UI helpers/tests for aggregate route editing and validation

Details

• Supports patterns such as deepseek-*, gpt-*, and exact model names.
• Keeps legacy aggregate strategies for unmatched requests.
• Skips invalid route targets and records route matched / unmatched / skipped diagnostic events.
• Falls back through remaining aggregate members when the selected upstream request fails.

Closes #1744.

Test plan

• npm test
• npm run check
• cargo test -p codex-plus-core --test relay_rotation
• cargo test -p codex-plus-core --test protocol_proxy aggregate -- --nocapture
• cargo test -p codex-plus-core --test relay_config aggregate -- --nocapture
• cargo test -p codex-plus-core --test relay_switch