feat: codex 5.4 default and pass to model

[k11kirky]

Problem

Codex was not respecting model choice
Default changed to 5.4

Changes

• Added DEFAULT_CODEX_MODEL constant set to "gpt-5.4" in gateway-models.ts
• Updated model selection logic to prefer the default Codex model when available, falling back to the first model only if the default is not in the available options
• Passed the resolved model parameter to the Agent constructor to ensure consistent model usage

How did you test this?

Manual

[k11kirky]

• feat: Harden CodexAcpAgent session state and permission handling #1487
• feat: give codex permissions support #1483
• feat: give codex system prompt via personality #1482
• feat: clean up session reloadin #1481
• feat: update codex adapter and migrate to base acp prxy for agent #1480
• feat: codex 5.4 default and pass to model #1479 👈 (View in Graphite)
• main

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