fix(discord): non-owners no longer see a stuck "Loading…" on the servers card (#213)

The card only loads for owners/admins (the list endpoint is owner-only), so a
member saw "Loading…" forever. Show an owner-only note instead. Also assert the
one-server/two-org race really retried, as the PR body already claimed.

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

drb-c2-core/tests/test_discord_guild_link.py

@@ -147,6 +147,7 @@ async def test_one_server_racing_two_orgs_codes_ends_on_exactly_one(fs):
     b = await _mint(OWNER_B)
     _hold_both_at_commit(fs)
     r1, r2 = await asyncio.gather(_redeem(a["code"], user="u1"), _redeem(b["code"], user="u2"))
+    assert fs.retries >= 1                                   # the race really happened
     assert sorted([_status(r1), _status(r2)]) == [200, 409]
     winner = "org-a" if _status(r1) == 200 else "org-b"
     loser_code = b["code"] if winner == "org-a" else a["code"]

drb-frontend/components/DiscordServersCard.tsx

@@ -171,7 +171,10 @@ export function DiscordServersCard({ canEdit, isAdmin }: { canEdit: boolean; isA
             </tr>
           </thead>
           <tbody>
-            {guilds === null && !loadError && (
+            {!canEdit && (
+              <tr><td colSpan={4} className="px-5 py-4 text-xs text-ink-muted">Only the organization owner can see and link Discord servers.</td></tr>
+            )}
+            {canEdit && guilds === null && !loadError && (
               <tr><td colSpan={4} className="px-5 py-4 text-xs text-ink-muted">Loading…</td></tr>
             )}
             {loadError && (