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/CreateRoomModal.svelte

@@ -0,0 +1,103 @@
+<script lang="ts">
+  import { Button, Input } from "$lib/components/ui";
+  import { createRoom } from "$lib/matrix";
+  import { toasts } from "$lib/stores/ui";
+  import { syncRoomsFromEvent, selectRoom } from "$lib/stores/matrix";
+
+  interface Props {
+    isOpen: boolean;
+    onClose: () => void;
+  }
+
+  let { isOpen, onClose }: Props = $props();
+
+  let roomName = $state("");
+  let isDirect = $state(false);
+  let isCreating = $state(false);
+
+  async function handleCreate() {
+    if (!roomName.trim()) {
+      toasts.error("Please enter a room name");
+      return;
+    }
+
+    isCreating = true;
+
+    try {
+      const result = await createRoom(roomName.trim(), isDirect);
+      toasts.success("Room created!");
+
+      // Add new room to list and select it
+      syncRoomsFromEvent("join", result.room_id);
+      selectRoom(result.room_id);
+
+      // Reset and close
+      roomName = "";
+      isDirect = false;
+      onClose();
+    } catch (e: any) {
+      console.error("Failed to create room:", e);
+      toasts.error(e.message || "Failed to create room");
+    } finally {
+      isCreating = false;
+    }
+  }
+
+  function handleKeyDown(e: KeyboardEvent) {
+    if (e.key === "Escape") {
+      onClose();
+    }
+  }
+</script>
+
+{#if isOpen}
+  <div
+    class="fixed inset-0 bg-black/70 flex items-center justify-center z-50"
+    onclick={onClose}
+    onkeydown={handleKeyDown}
+    role="dialog"
+    aria-modal="true"
+    tabindex="-1"
+  >
+    <div
+      class="bg-dark rounded-2xl p-6 w-full max-w-md mx-4"
+      onclick={(e) => e.stopPropagation()}
+      role="document"
+    >
+      <h2 class="text-xl font-semibold text-light mb-4">Create New Room</h2>
+
+      <form
+        onsubmit={(e) => {
+          e.preventDefault();
+          handleCreate();
+        }}
+        class="flex flex-col gap-4"
+      >
+        <Input
+          bind:value={roomName}
+          label="Room Name"
+          placeholder="My awesome room"
+          required
+        />
+
+        <label class="flex items-center gap-3 text-light cursor-pointer">
+          <input
+            type="checkbox"
+            bind:checked={isDirect}
+            class="w-4 h-4 rounded border-light/30 bg-night text-primary focus:ring-primary"
+          />
+          <span>Direct message (private 1:1 chat)</span>
+        </label>
+
+        <div class="flex gap-3 justify-end mt-2">
+          <Button variant="secondary" onclick={onClose} disabled={isCreating}>
+            Cancel
+          </Button>
+          <Button type="submit" loading={isCreating} disabled={isCreating}>
+            {isCreating ? "Creating..." : "Create Room"}
+          </Button>
+        </div>
+      </form>
+    </div>
+  </div>
+{/if}