feat: integrate Matrix chat (Option 2 - credentials stored in Supabase)

- Add matrix-js-sdk, marked, highlight.js, twemoji, @tanstack/svelte-virtual deps
- Copy Matrix core layer: /matrix/, /stores/matrix.ts, /cache/, /services/
- Copy Matrix components: matrix/, message/, chat-layout/, chat-settings/
- Copy UI components: EmojiPicker, Twemoji, ImagePreviewModal, VirtualList
- Copy utils: emojiData, twemoji, twemojiGlobal
- Replace lucide-svelte with Material Symbols in SyncRecoveryBanner
- Extend Avatar with xs size and status indicator prop
- Fix ui.ts store conflict: re-export toasts from toast.svelte.ts
- Add migration 020_matrix_credentials for storing Matrix tokens per user/org
- Add /api/matrix-credentials endpoint (GET/POST/DELETE)
- Create [orgSlug]/chat page with Matrix login form + full chat UI
- Add Chat to sidebar navigation

src/lib/components/matrix/MemberList.svelte

@@ -0,0 +1,102 @@
+<script lang="ts">
+  import { Avatar } from "$lib/components/ui";
+  import UserProfileModal from "./UserProfileModal.svelte";
+  import type { RoomMember } from "$lib/matrix/types";
+  import { userPresence } from "$lib/stores/matrix";
+
+  interface Props {
+    members: RoomMember[];
+    onMemberClick?: (member: RoomMember) => void;
+    onStartDM?: (roomId: string) => void;
+  }
+
+  let { members, onMemberClick, onStartDM }: Props = $props();
+
+  let selectedMember = $state<RoomMember | null>(null);
+
+  function handleMemberClick(member: RoomMember) {
+    if (onMemberClick) {
+      onMemberClick(member);
+    } else {
+      selectedMember = member;
+    }
+  }
+
+  // Sort: online first, then admins, then by name
+  const sortedMembers = $derived(
+    [...members].sort((a, b) => {
+      // Online status first
+      const aOnline = $userPresence.get(a.userId) === "online" ? 1 : 0;
+      const bOnline = $userPresence.get(b.userId) === "online" ? 1 : 0;
+      if (bOnline !== aOnline) return bOnline - aOnline;
+
+      // Power level descending
+      if (b.powerLevel !== a.powerLevel) {
+        return b.powerLevel - a.powerLevel;
+      }
+      // Then alphabetically
+      return a.name.localeCompare(b.name);
+    }),
+  );
+
+  function getRoleBadge(
+    powerLevel: number,
+  ): { label: string; color: string } | null {
+    if (powerLevel >= 100) return { label: "Admin", color: "text-red-400" };
+    if (powerLevel >= 50) return { label: "Mod", color: "text-yellow-400" };
+    return null;
+  }
+
+  function getPresenceStatus(userId: string): "online" | "offline" | null {
+    const presence = $userPresence.get(userId);
+    if (presence === "online") return "online";
+    if (presence === "offline" || presence === "unavailable") return "offline";
+    return null;
+  }
+</script>
+
+<div class="flex flex-col h-full">
+  <header class="p-4 border-b border-light/10">
+    <h3 class="font-semibold text-light">Members ({members.length})</h3>
+  </header>
+
+  <div class="flex-1 overflow-y-auto">
+    {#each sortedMembers as member}
+      <button
+        class="w-full flex items-center gap-3 px-4 py-2 hover:bg-light/5 transition-colors text-left"
+        onclick={() => handleMemberClick(member)}
+      >
+        <Avatar
+          src={member.avatarUrl}
+          name={member.name}
+          size="sm"
+          status={getPresenceStatus(member.userId)}
+        />
+        <div class="flex-1 min-w-0">
+          <div class="flex items-center gap-2">
+            <span class="text-light truncate">{member.name}</span>
+            {#if getRoleBadge(member.powerLevel)}
+              {@const badge = getRoleBadge(member.powerLevel)}
+              <span class="text-xs {badge?.color}">{badge?.label}</span>
+            {/if}
+          </div>
+          <p class="text-xs text-light/40 truncate">{member.userId}</p>
+        </div>
+      </button>
+    {/each}
+
+    {#if members.length === 0}
+      <div class="p-4 text-center text-light/40">
+        <p>No members</p>
+      </div>
+    {/if}
+  </div>
+</div>
+
+{#if selectedMember}
+  <UserProfileModal
+    member={selectedMember}
+    onClose={() => (selectedMember = null)}
+    {onStartDM}
+  />
+{/if}