Codex Config Generated Bundle Follow-Up

PR: #5566 Branch: code-yeongyu/fix-codex-config-migration

Scope

• Preserve explicit legacy [features] multi_agent_v2 = false as [features.multi_agent_v2] enabled = false.
• Keep installer behavior aligned between TypeScript source and shipped packages/omo-codex/scripts/install-dist/install-local.mjs.
• Prove the generated public installer surface no longer drops the disabled setting.

Evidence

• build-codex-install.txt: regenerated the shipped installer bundle.
• source-config-tests.txt: bun test packages/omo-codex/src/install/codex-config-toml.test.ts packages/omo-codex/src/install/codex-multi-agent-v2-config.test.ts, 21 pass / 0 fail.
• generated-config-and-bundle-tests.txt: node --test packages/omo-codex/scripts/install-generated-bundle.test.mjs packages/omo-codex/scripts/install-config.test.mjs, 19 pass / 0 fail.
• generated-bundle-false-shorthand-probe.txt: direct generated-bundle probe showing legacy multi_agent_v2 = false becomes a disabled table with max_concurrent_threads_per_session = 10000.
• install-verify.txt: codex-qa isolated install verification passed; real ~/.codex/config.toml unchanged.
• typecheck-omo-codex.txt: tsgo --noEmit -p packages/omo-codex/tsconfig.json passed.
• git-diff-check.txt: whitespace/conflict-marker check passed.