feat: server members API + member list in sidebar + fix chat input

Backend:
- Add GET /api/v1/servers/{serverID}/members endpoint
- Wire MemberHandler routes in main.go

Frontend:
- Create member store (fetchMembers by server ID)
- MemberList now fetches members from API instead of empty props
- ChatArea: show channel name instead of ID, add error display,
  add flex-1 + min-w-0 to input for proper sizing, error handling
  on sendMessage

web/src/components/MemberList.tsx

@@ -1,83 +1,85 @@
-import { usePresenceStore } from '../stores/presence.ts';
-import type { User, UserStatus } from '../stores/auth.ts';
-
-interface MemberListProps {
-  members?: User[];
-}
+import { useEffect } from "react";
+import { useServerStore } from "../stores/server.ts";
+import { useMemberStore, type Member } from "../stores/member.ts";
+import { usePresenceStore } from "../stores/presence.ts";
+import type { UserStatus } from "../stores/auth.ts";
 
 function statusIcon(status: UserStatus): string {
   switch (status) {
-    case 'online':
-      return '\u25cf';
-    case 'idle':
-      return '\u25d0';
-    case 'dnd':
-      return '\u26d5';
+    case "online":
+      return "\u25cf";
+    case "idle":
+      return "\u25d0";
+    case "dnd":
+      return "\u26d5";
     default:
-      return '\u25cb';
+      return "\u25cb";
   }
 }
 
 function statusColor(status: UserStatus): string {
   switch (status) {
-    case 'online':
-      return 'text-gb-green';
-    case 'idle':
-      return 'text-gb-yellow';
-    case 'dnd':
-      return 'text-gb-red';
+    case "online":
+      return "text-gb-green";
+    case "idle":
+      return "text-gb-yellow";
+    case "dnd":
+      return "text-gb-red";
     default:
-      return 'text-gb-gray';
+      return "text-gb-gray";
   }
 }
 
 function usernameColor(status: UserStatus): string {
   switch (status) {
-    case 'online':
-      return 'text-gb-aqua';
-    case 'idle':
-      return 'text-gb-yellow';
-    case 'dnd':
-      return 'text-gb-red';
+    case "online":
+      return "text-gb-aqua";
+    case "idle":
+      return "text-gb-yellow";
+    case "dnd":
+      return "text-gb-red";
     default:
-      return 'text-gb-fg-f';
+      return "text-gb-fg-f";
   }
 }
 
-/** Return the live status for a member, falling back to the static value. */
-function useLiveStatus(member: User): UserStatus {
+function MemberRow({ member }: { member: Member }) {
   const presence = usePresenceStore((s) => s.presences[member.id]);
-  return presence?.status ?? member.status;
-}
-
-interface MemberRowProps {
-  member: User;
-}
-
-function MemberRow({ member }: MemberRowProps) {
-  const status = useLiveStatus(member);
+  const status = presence?.status ?? member.status;
 
   return (
     <div className="flex items-center gap-2 px-2 py-1">
       <span className={statusColor(status)}>{statusIcon(status)}</span>
       <span className={`truncate ${usernameColor(status)}`}>
-        {member.username}
+        {member.display_name || member.username}
       </span>
     </div>
   );
 }
 
-export function MemberList({ members = [] }: MemberListProps) {
-  // Derive live status for every member to decide online/offline buckets.
+export function MemberList() {
+  const activeServerId = useServerStore((s) => s.activeServerId);
+  const membersByServer = useMemberStore((s) => s.membersByServer);
+  const fetchMembers = useMemberStore((s) => s.fetchMembers);
   const presences = usePresenceStore((s) => s.presences);
 
+  const members = activeServerId
+    ? membersByServer[activeServerId] || []
+    : [];
+
+  useEffect(() => {
+    if (activeServerId) {
+      fetchMembers(activeServerId);
+    }
+  }, [activeServerId, fetchMembers]);
+
   const online = members.filter((m) => {
     const status = presences[m.id]?.status ?? m.status;
-    return status !== 'offline';
+    return status !== "offline";
   });
   const offline = members.filter((m) => {
     const status = presences[m.id]?.status ?? m.status;
-    return status === 'offline';
+    return status === "offline";
   });
 
   return (
@@ -86,15 +88,18 @@ export function MemberList({ members = [] }: MemberListProps) {
         [MEMBERS]
       </div>
       <div className="flex-1 overflow-y-auto p-2 font-mono text-sm">
-        {members.length === 0 && (
+        {!activeServerId && (
+          <p className="text-gb-fg-f">[select a server]</p>
+        )}
+        {activeServerId && members.length === 0 && (
           <p className="text-gb-fg-f">[no members]</p>
         )}
         {online.length > 0 && (
           <div className="mb-3">
             <div className="text-gb-fg-t text-xs uppercase mb-1">ONLINE</div>
             <div className="text-gb-fg-f text-xs mb-1">---</div>
-            {online.map((member) => (
-              <MemberRow key={member.id} member={member} />
+            {online.map((m) => (
+              <MemberRow key={m.id} member={m} />
             ))}
           </div>
         )}
@@ -102,8 +107,8 @@ export function MemberList({ members = [] }: MemberListProps) {
           <div>
             <div className="text-gb-fg-t text-xs uppercase mb-1">OFFLINE</div>
             <div className="text-gb-fg-f text-xs mb-1">---</div>
-            {offline.map((member) => (
-              <MemberRow key={member.id} member={member} />
+            {offline.map((m) => (
+              <MemberRow key={m.id} member={m} />
             ))}
           </div>
         )}