Discord admin overview: no fallback org for explicitly unlinked servers

PR #218 (server-26#213 item 1) unlinks a server by clearing org_id and
stamping unlinked_at, and resolve_guild_org then refuses the fallback org.
The overview showed such a server as "Unlinked · fallback org" and offered it
in Add radio channel, where start_stream would 403. Mirror the rule here
(forward-compatible: unlinked_at does not exist on main yet). Also key each
stream row by the resolved guild id, and drop panel copy that pointed at a
"Needed" figure the page doesn't show / misstated the invite permissions.

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

drb-frontend/components/discord/RadioBotsPanel.tsx

@@ -185,7 +185,7 @@ export function RadioBotsPanel({
   return (
     <Panel
       title="Radio bots"
-      description="Each bot can be in one voice channel per server, in many servers at once. Needed = most simultaneous channels in any one server."
+      description="Each bot can be in one voice channel per server, in many servers at once."
       action={
         <>
           {leased > 0 && (
@@ -209,7 +209,7 @@ export function RadioBotsPanel({
       note={
         <>
           <b className="text-ink">Release is ordered:</b> the node stops the bot&apos;s gateway session, then acks, then the
-          token returns to the pool — a token is never live on two nodes. Invite links ask for Connect + Speak only.
+          token returns to the pool — a token is never live on two nodes. Invite links ask for View Channel, Connect and Speak only.
         </>
       }
     >