test: add an opt-in live Codex test

[TheGreatAxios]

Closes CL-9405

Summary

• Adds e2e/live.test.ts: one streamed text turn through runInference against the ChatGPT Codex backend, with fetch wrapped in withCodexContentTypeRepair and the account id passed as providerOptions.codexAccountId.
• Skipped unless both CODEX_LIVE_ACCESS_TOKEN and CODEX_LIVE_ACCOUNT_ID are set. CODEX_LIVE_MODEL defaults to gpt-5.5.
• Adds test:e2e (bun test e2e), sets test to bun test src, adds e2e to the tsconfig include, and removes bunfig.toml, whose [test] root = "src" kept bun test e2e from finding the suite.

Checks

• bun run check: 13 pass. bun run test:e2e: 1 skip.
• Not run against the real backend (no token). With a placeholder token the suite reaches the backend and gets Unauthorized, which confirms the wiring.