fix(cursor): nest ACP extension outcome so plan approvals aren't cancelled

[heavygee]

Summary

Fixes #79. Approving a Cursor plan-mode CreatePlan request from the HAPI web UI relayed User cancelled back to the agent instead of an approval, so the plan → execute handoff never fired (plan mode unusable for Cursor sessions over HAPI).

Root cause: Cursor's ACP blocking extension methods (cursor/ask_question, cursor/create_plan) require the JSON-RPC result to nest the outcome under an outcome key (see https://cursor.com/docs/cli/acp):

interface CursorCreatePlanResponse {
  outcome:
    | { outcome: "accepted"; planUri?: string }
    | { outcome: "rejected"; reason?: string }
    | { outcome: "cancelled" };
}

cli/src/cursor/utils/cursorExtensionAdapter.ts returned the outcome flat ({ outcome: "accepted" }), so Cursor read response.outcome.outcome as undefined and fell back to a cancellation. The hub still recorded the request as approved (green checkmark), which is why the symptom looked like "approved in the UI, cancelled to the agent". The same flat shape affected cursor/ask_question (identical latent bug).

The standard ACP session/request_permission responses in AcpSdkBackend already use the nested { outcome: { outcome: ... } } shape, so the cursor extension responses were the outlier.

Changes

• Wrap all cursor/ask_question and cursor/create_plan responses (accept / reject / cancel / answered, incl. cancelAll) in the nested { outcome: { ... } } envelope via a small wrapOutcome helper.
• Update existing adapter tests to assert the nested wire shape.
• Add regression tests: affirmative approval → CreatePlan (approved and approved_for_session) resolves to { outcome: { outcome: 'accepted' } }, plus reject → rejected and abort → cancelled.

Test plan

• bun typecheck (cli/web/hub) green
• bun run test green (cli + hub)
• cursorExtensionAdapter.test.ts — 12/12 pass
• Manual: Cursor plan-mode session on a hub, click Yes on a CreatePlan approval, confirm the agent proceeds (plan accepted) rather than receiving User cancelled.