feat(discord): add exec approval forwarding to DMs (#1621)

* feat(discord): add exec approval forwarding to DMs

Add support for forwarding exec approval requests to Discord DMs,
allowing users to approve/deny command execution via interactive buttons.

Features:
- New DiscordExecApprovalHandler that connects to gateway and listens
  for exec.approval.requested/resolved events
- Sends DMs with embeds showing command details and 3 buttons:
  Allow once, Always allow, Deny
- Configurable via channels.discord.execApprovals with:
  - enabled: boolean
  - approvers: Discord user IDs to notify
  - agentFilter: only forward for specific agents
  - sessionFilter: only forward for matching session patterns
- Updates message embed when approval is resolved or expires

Also fixes exec completion routing: when async exec completes after
approval, the heartbeat now uses a specialized prompt to ensure the
model relays the result to the user instead of responding HEARTBEAT_OK.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* feat: generic exec approvals forwarding (#1621) (thanks @czekaj)

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/config/zod-schema.ts

@@ -1,5 +1,6 @@
 import { z } from "zod";
 import { ToolsSchema } from "./zod-schema.agent-runtime.js";
+import { ApprovalsSchema } from "./zod-schema.approvals.js";
 import { AgentsSchema, AudioSchema, BindingsSchema, BroadcastSchema } from "./zod-schema.agents.js";
 import { HexColorSchema, ModelsConfigSchema } from "./zod-schema.core.js";
 import { HookMappingSchema, HooksGmailSchema, InternalHooksSchema } from "./zod-schema.hooks.js";
@@ -220,6 +221,7 @@ export const ClawdbotSchema = z
       .optional(),
     messages: MessagesSchema,
     commands: CommandsSchema,
+    approvals: ApprovalsSchema,
     session: SessionSchema,
     cron: z
       .object({