Discord: log node-reported stream state; remove a radio channel or a server

- handle_actual logs every node-reported state TRANSITION (not heartbeats)
  with stream/node/guild/channel/token ids and the node's error text: info
  for connected/connecting/stopped, warning for error, and a dedicated
  "radio bot X failed to log in on node N: <reason>" line for login_failed.
  The node's reason code is now stored in actual.code and shown next to the
  error on Settings > Discord and the node page.
- Remove a radio channel permanently: streams.delete_stream stops it through
  desired state first (node republished without it, token -> releasing per
  #216, freed on the node's ack), then deletes the doc in a transaction that
  refuses if the channel was restarted in between. DELETE
  /discord/streams/{id} (platform admin) and DELETE
  /discord/nodes/{node}/streams/{id} (admin or org owner, same org + node
  only; operators can still stop, not remove). Audited.
- Remove a server: DELETE /discord/guilds/{id} (admin) deletes every radio
  channel in it the same way, then tombstones discord_guilds (org_id None +
  unlinked_at, #218 semantics, plus removed_at) so it never falls back to
  DISCORD_UNLINKED_GUILD_ORG_ID; the admin page hides it, and /drb link or the
  admin link brings it back. Optional leave_radio_bots makes pool bots and the
  server's org's own BYO bots leave via Discord REST; the DRB server bot stays
  until kicked, and the UI says so. Audited.
- UI: Remove (with confirm) on Radio channels, Servers and the node page list.

Refs #213, #221

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

drb-frontend/components/discord/StreamsPanel.tsx

@@ -18,6 +18,8 @@ import { DIM, Field, INPUT, InviteLinks, Panel, Status, Table, TD } from "./ui";
 // Radio channels = discord_streams docs, desired vs actual. Start/Stop/Add go
 // through the same routes the Discord bot uses (POST /discord/streams,
 // POST /discord/guilds/{id}/stop), which accept a platform-admin token.
+// Remove is DELETE /discord/streams/{id} (admin): c2-core stops the channel
+// through desired state first, then deletes it.
 
 type Invite = { name: string; invite_url: string | null }[];
 
@@ -214,7 +216,12 @@ export function StreamsPanel({
                 <td className={TD}>{s.mode === "adhoc" ? "ad-hoc" : s.mode ?? "—"}</td>
                 <td className={TD}>
                   <Status health={health}>{label}</Status>
-                  {isOn && s.actual?.error && <div className={`${DIM} mt-1 max-w-[16rem]`}>{s.actual.error}</div>}
+                  {isOn && s.actual?.error && (
+                    <div className={`${DIM} mt-1 max-w-[16rem]`}>
+                      {s.actual.error}
+                      {s.actual.code && <span className="font-mono"> [{s.actual.code}]</span>}
+                    </div>
+                  )}
                   {!isOn && s.stop_reason && <div className={`${DIM} mt-1`}>{s.stop_reason}</div>}
                   {err && (
                     <div className="text-xs text-sev-major mt-1 max-w-[16rem]">
@@ -224,7 +231,7 @@ export function StreamsPanel({
                   )}
                 </td>
                 <td className={TD}>{s.token_name ?? <span className={DIM}>—</span>}</td>
-                <td className={`${TD} text-right`}>
+                <td className={`${TD} text-right whitespace-nowrap`}>
                   {isOn ? (
                     <Button
                       size="sm"
@@ -256,6 +263,22 @@ export function StreamsPanel({
                       {busy === s.stream_id ? "Starting…" : "Start"}
                     </Button>
                   )}
+                  <Button
+                    size="sm"
+                    variant="danger"
+                    className="ml-1"
+                    disabled={busy !== null}
+                    onClick={() => {
+                      const name = s.channel_name || "this channel";
+                      const msg = isOn
+                        ? `Remove radio from ${name} permanently? It is stopped first (the node logs its radio bot out), then deleted from DRB.`
+                        : `Remove ${name} from DRB permanently?`;
+                      if (!confirm(msg)) return;
+                      act(s, () => c2api.deleteDiscordStream(s.stream_id));
+                    }}
+                  >
+                    Remove
+                  </Button>
                 </td>
               </tr>
             );