v2.3.1-permission-questions: enrich ACP permission wire for interactive questions and elicitations

The permission_requested WS frame now carries kind ('tool'|'question'|'plan'|
'elicitation'), input (the tool's rawInput payload), and description fields.
PermissionCard detects question-type permissions (Claude Code's AskUserQuestion)
and renders an interactive radio/checkbox form instead of approve/deny buttons.
Submitting answers auto-selects the first allow option.

Also wires up ACP createElicitation (unstable/experimental) — JSON Schema-driven
forms for structured user input. The same PermissionCard renders elicitation
fields with type-appropriate inputs. Both flows use the existing permission-waiter
blocking pattern with 120s timeout.

The response path (POST /api/coder/tasks/:id/permission) now accepts optional
updated_input alongside option_id, forwarded to the ACP agent as the user's
answer payload. Elicitation responses map to accept/decline/cancel actions.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/coder/src/services/acp-dispatch.ts

@@ -17,6 +17,8 @@ import {
   type WriteTextFileResponse,
   type CreateTerminalRequest,
   type CreateTerminalResponse,
+  type CreateElicitationRequest,
+  type CreateElicitationResponse,
   type SessionConfigOption,
   type ClientSideConnection as ConnectionType,
 } from '@agentclientprotocol/sdk';
@@ -26,7 +28,7 @@ import { spawn } from 'node:child_process';
 import { findThoughtLevelConfigId } from './acp-derive.js';
 import { resolveAcpSpawnArgs } from './acp-spawn.js';
 import { createAcpNdJsonStream } from './acp-stream.js';
-import { waitForPermissionResponse, cancelPendingPermission } from './permission-waiter.js';
+import { waitForPermissionResponse, waitForElicitationResponse, cancelPendingPermission } from './permission-waiter.js';
 import { mergeTaskCommands, getTaskCommands } from './agent-commands-cache.js';
 import { readWorktreeTextFile, writeWorktreeTextFile } from './acp-client-fs.js';
 import {
@@ -254,6 +256,12 @@ class AcpStreamContext {
       createTerminal: async (_params: CreateTerminalRequest): Promise<CreateTerminalResponse> => {
         return { terminalId: 'noop' };
       },
+      unstable_createElicitation: async (params: CreateElicitationRequest): Promise<CreateElicitationResponse> => {
+        if (taskId && sessionId) {
+          return waitForElicitationResponse(taskId, sessionId, agent, modeId, params);
+        }
+        return { action: 'decline' };
+      },
     };
   }
 }