feat: bridge Codex dynamic tools through ACP

[gaofeng21cn]

Summary

• accept a versioned codex/dynamic_tools registry in ACP session/new._meta
• inject those specs into the experimental Codex thread/start.dynamicTools field without regenerating the full experimental schema
• forward Codex App Server item/tool/call requests through the typed ACP extension _codex/dynamic_tool_call
• multiplex callbacks once per shared MessageConnection, route by explicit session/thread ownership, and revoke all claimants on terminal thread/closed

Failure semantics

Malformed registration metadata fails with ACP invalid_params before thread/start. Unknown or duplicate owners, stale turns, closed sessions, disposed clients, missing dispatchers, and dispatcher failures return typed success: false. Ordinary thread notifications remain unique-owner only. Terminal thread/closed clears every claimant, so disposing one ambiguous claimant cannot resurrect a closed route.

Validation

Validated on 24589322f1f6a2e7a9fba6ebb42067e47e4dfffd:

• focused dynamic/session tests: 95 passed
• full npm test: 312 passed, 28 skipped
• npm run typecheck
• npm run build
• git diff --check HEAD^ HEAD
• fork HTTPS/SSH:443 readback exact

Cross-repo evidence

• AionCore host dispatcher: feat(acp): dispatch dynamic tools through websocket iOfficeAI/AionCore#619 at e1e022c9e327870bebefa26e417dc5f482349e10
• downstream Shell registration and live round-trip: 103b078af91454e9938f417fda0fde5ad52554b7
• Shell repository-native gate: 1,613 tests passed plus lint, format, typecheck, and i18n

This PR is ready for upstream review. The fork branch remains a contribution head only. Product completion still requires both upstream canonical mains to merge and the Shell to consume released canonical refs; no product dependency points at the fork.

[gaofeng21cn]

Cross-repo host half is now available as draft iOfficeAI/AionCore#619.

Immutable AionCore contribution head: e1e022c9e327870bebefa26e417dc5f482349e10 (parent 073f0ff2855f2fef2b3744df9bcac2e5b973a942).

The host dispatcher preserves conversation, WebSocket connection, registration generation, thread, turn, call, namespace, and tool identity; ambiguous ownership stays fail-closed after disconnect until explicit re-registration. Disconnect cleanup cancels pending calls. AionCore verification passed API types 2/2, registry 5/5, realtime 81/81, WebSocket E2E 21/21, AI-agent 617/617, affected strict clippy, workspace build, workspace cargo test, and repository-native just push (migration + workspace clippy/fmt + nextest). HTTPS and SSH:443 both read back the exact head.

Both PRs remain draft pending downstream Shell registration and a live round-trip against exact contribution refs.