feat(acp): dispatch dynamic tools through websocket

[gaofeng21cn]

Summary

• add typed WebSocket registration, call, result, and acknowledgement messages for Codex dynamic tools
• bind registrations to conversation, connection, generation, ACP thread, and turn identity
• dispatch ACP extension requests through the owning WebSocket and fail closed for unknown, ambiguous, stale, disconnected, timed-out, or mismatched results
• clean registrations and pending calls deterministically on WebSocket disconnect without logging tool arguments or result bodies

Protocol

This is the AionCore host half of agentclientprotocol/codex-acp#301.

WebSocket events:

• agent.dynamicToolsRegister
• agent.dynamicToolsRegistered
• agent.dynamicToolCall
• agent.dynamicToolResult

ACP session metadata uses codex/dynamic_tools; the extension request is codex/dynamic_tool_call. Ambiguous ownership is sticky fail-closed: disconnecting one claimant does not resurrect another claimant; a new explicit registration is required.

Validation

Validated on e1e022c9e327870bebefa26e417dc5f482349e10:

• API dynamic type tests: 2 passed
• dynamic registry tests: 5 passed
• realtime tests: 81 passed
• App WebSocket E2E: 21 passed
• AI agent suite: 617 passed
• affected crate strict clippy and cargo build --workspace
• cargo test --workspace
• repository-native just push
• git diff --check HEAD^ HEAD
• fork HTTPS/SSH:443 readback exact

Cross-repo evidence

• codex-acp extension: feat: bridge Codex dynamic tools through ACP agentclientprotocol/codex-acp#301 at 24589322f1f6a2e7a9fba6ebb42067e47e4dfffd
• 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 checkpoint, not a canonical product carrier. Product completion still requires both upstream canonical mains to merge and the Shell to consume released canonical refs.