feat(discord): add configurable privileged Gateway Intents (GuildPresences, GuildMembers) (#2266)

* feat(discord): add configurable privileged Gateway Intents (GuildPresences, GuildMembers)

Add support for optionally enabling Discord privileged Gateway Intents
via config, starting with GuildPresences and GuildMembers.

When `channels.discord.intents.presence` is set to true:
- GatewayIntents.GuildPresences is added to the gateway connection
- A PresenceUpdateListener caches user presence data in memory
- The member-info action includes user status and activities
  (e.g. Spotify listening activity) from the cache

This enables use cases like:
- Seeing what music a user is currently listening to
- Checking user online/offline/idle/dnd status
- Tracking user activities through the bot API

Both intents require Portal opt-in (Discord Developer Portal →
Privileged Gateway Intents) before they can be used.

Changes:
- config: add `channels.discord.intents.{presence,guildMembers}`
- provider: compute intents dynamically from config
- listeners: add DiscordPresenceListener (extends PresenceUpdateListener)
- presence-cache: simple in-memory Map<userId, GatewayPresenceUpdate>
- discord-actions-guild: include cached presence in member-info response
- schema: add labels and descriptions for new config fields

* fix(test): add PresenceUpdateListener to @buape/carbon mock

* Discord: scope presence cache by account

---------

Co-authored-by: kugutsushi <kugutsushi@clawd>
Co-authored-by: Shadow <hi@shadowing.dev>

src/config/zod-schema.providers-core.ts

@@ -256,6 +256,13 @@ export const DiscordAccountSchema = z
       })
       .strict()
       .optional(),
+    intents: z
+      .object({
+        presence: z.boolean().optional(),
+        guildMembers: z.boolean().optional(),
+      })
+      .strict()
+      .optional(),
   })
   .strict();