Node page Discord picker: org's linked servers + voice channels, not raw IDs (#213 item 3, #109 item 13)

- c2-core routers/discord_web.py:
  PUT  /discord/guilds/{id}/directory (service key): the server bot pushes each
       server's name + voice channels; merged onto discord_guilds, never touches org_id.
  GET  /discord/nodes/{id}/join-options: the node org's servers (same
       resolve rule as the bot), their voice channels with any live stream,
       radio-bot readiness + invite links, and this node's streams. No tokens.
  POST /discord/nodes/{id}/streams: stream pinned to the node; server must be
       the node org's, channel must be in the bot's directory, guild + node caps.
  POST /discord/nodes/{id}/streams/stop: one stream on this node, or all.
  Control = platform admin, org owner, or operator owning the node.
- nodes.py: legacy raw-ID discord_join now refuses a server outside the node's org.
- discord bot: DirectorySync cog pushes on ready (15-min loop), join/leave,
  rename, voice/category channel changes (debounced).
- frontend: NodeDiscordRadio panel + picker replaces DiscordJoinModal and the
  admin-only Join/Leave buttons.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-frontend/lib/c2api.ts

@@ -73,6 +73,21 @@ export const c2api = {
     ),
   rejectNode: (id: string) =>
     request(`/nodes/${id}/reject`, { method: "POST" }),
+
+  // Node-page Discord picker (server-26#213 item 3) — org-scoped server side.
+  getNodeDiscordOptions: (nodeId: string) =>
+    request<import("@/lib/discordPicker").DiscordJoinOptions>(`/discord/nodes/${nodeId}/join-options`),
+  startNodeDiscordStream: (nodeId: string, body: { guild_id: string; channel_id: string; mode: "adhoc" | "persistent" }) =>
+    request<import("@/lib/discordPicker").DiscordStartResult>(`/discord/nodes/${nodeId}/streams`, {
+      method: "POST",
+      body: JSON.stringify(body),
+    }),
+  /** Omit streamId to stop every radio channel this node carries. */
+  stopNodeDiscordStreams: (nodeId: string, streamId?: string) =>
+    request<{ ok: boolean; stopped: string[] }>(`/discord/nodes/${nodeId}/streams/stop`, {
+      method: "POST",
+      body: JSON.stringify(streamId ? { stream_id: streamId } : {}),
+    }),
   deleteNode: (id: string) =>
     request(`/nodes/${id}`, { method: "DELETE" }),