feat(models): add gpt-5.3-codex model support

[professional-ALFIE]

Summary (요약)

• MODEL_FAMILIES 배열에 "gpt-5.3-codex"를 첫 번째(최신) 모델로 추가
• PROMPT_FILES, CACHE_FILES 매핑 추가 (gpt-5.2-codex 파일 재사용)
• getModelFamily()에 gpt-5.3-codex 패턴 인식 로직 추가
• AccountManager 초기값에 gpt-5.3-codex 추가

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Summary (English)

• Add "gpt-5.3-codex" to MODEL_FAMILIES array as the first (latest) model
• Add PROMPT_FILES and CACHE_FILES mappings (reusing gpt-5.2-codex files)
• Add gpt-5.3-codex pattern recognition in getModelFamily()
• Add AccountManager initial values for gpt-5.3-codex

Changes

File	Changes
lib/constants.ts	Add "gpt-5.3-codex" to MODEL_FAMILIES
lib/prompts/codex.ts	Add prompt/cache mappings and getModelFamily() branch
lib/accounts.ts	Add AccountManager initial values

Testing

• ✅ npm run typecheck passed
• ✅ npm test 446/446 tests passed
• ✅ test/models-gpt-5.3-codex.test.ts 4 tests passed

⚠️ Important Note

The official gpt-5.3-codex_prompt.md file does NOT exist yet in the upstream repository.

As of now, the OpenAI codex repository (codex-rs/core) only has:

• gpt-5.2-codex_prompt.md
• gpt-5.1-codex-max_prompt.md
• gpt_5_codex_prompt.md
• gpt_5_1_prompt.md
• gpt_5_2_prompt.md

There is no gpt-5.3-codex_prompt.md file available.

Current workaround: This PR reuses gpt-5.2-codex_prompt.md for gpt-5.3-codex. In my proxy testing, this works without issues - no 400/500 errors occurred when calling via Codex OAuth.

When the official prompt file becomes available, only the mapping in lib/prompts/codex.ts needs to be updated.

[iam-brain]

Hi @professional-ALFIE, I've just finished a massive refactor of the plugin and brought in 5.3 + added logic for automatic enablement of future models as well.

To achieve that, I had to dig into how Codex officially handles this logic & data and this plugin required a massive overhaul + refactor to use data served by the validation servers at OpenAI, PR #12 handles all of it and will be wrapped up as soon as possible. If you pull the current main & build locally, GPT-5.3 is already enabled preliminarily :)
Even personalities have been enabled, the codex bridge has finally been ripped out to stop confusion & slop with the agent, and a whole lot of other goodies.

[iam-brain]

@professional-ALFIE wanted to give you an update - unfortunately, the route I decided to go with this in reworking this plugin resulted in lackluster performance during use. forking from 4.6.0 and patching in 5.3 is your best choice for this plugin until my new plugin is done.

Currently wrapping up dev on a novel plugin based on the native openai plugin that should work a lot better with proper codex spoofing, better integration into opencode as it updates over time, and less jank that i've found to be core to the original plugin I forked here.. Should be ready before the weekend comes around, just need to flesh it out and do more testing.