feat: re-send undecided interaction requests to reconnected remote clients

[william0wang]

Problem

session/request_permission / elicitation/create are one-shot requests raced across the clients connected at fire time (first response wins). A remote client that was offline when the agent asked (or dropped mid-wait) never sees the request; after reconnecting it still cannot answer — the reannounce dedup only records zcode ids (no re-prompt) and the session/load replay only re-sends pending tool_call cards, not interaction requests.

Fix

• src/handlers/server-requests.ts: every interaction wait in requestWithTimeout is tracked as an ActiveInteraction — a cross-attempt first-response-wins race (method/params + deferred + per-attempt AbortControllers). The first attempt goes through the broadcast proxy as before; targeted re-sends join the same race and losers are aborted (SDK emits $/cancel_request, so Zed and the phone client dismiss their dialogs).
• src/index.ts: after a client's session/load / session/resume completes (the reconnect catch-up), resendPendingInteractions re-sends that session's still-unanswered interaction requests to it, 300 ms delayed so the replay renders first. Connect-time resend was rejected deliberately: the phone client clears permission/elicitation state when a load starts, which would swallow an immediately re-sent dialog.
• On wait settle (answered OR interrupted) the entry is unregistered and remaining attempts aborted — this also dismisses Zed's stale popup after a turn cancel (previous behavior left it open).
• A re-send client whose request throws synchronously is funnelled into the rejection path: the resend fires from a timer callback, where a sync throw would crash the bridge.

Verification

• 6 new tests in tests/interaction-resend.test.ts (reconnect adoption + loser cancel, session filtering, original-wins, interrupted-wait, already-answered, sync-throw survival).
• pnpm typecheck / pnpm lint / full suite (42 files, 658 tests) pass.
• Cross-checked the abort semantics against the ACP SDK source (abort only emits $/cancel_request; the request promise stays pending until the peer answers) and the phone client's onCancelRequest handling.
• docs/PROTOCOL.md: documented the reconnect-resend behavior in the interaction routing section.