fix: DM preview shows message body for E2EE rooms; filter inputs match members panel style

- RoomNavItem: change isEncrypted() to isDecryptionFailure() so DM
  previews show actual message body for successfully decrypted E2EE
  events instead of always showing 'Encrypted message'
- Home.tsx / Direct.tsx: upgrade filter inputs to size 400 / radii 400
  with search icon prefix to match the members list search bar style

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/features/room-nav/RoomNavItem.tsx

@@ -454,7 +454,7 @@ function RoomNavItem_({
     // Skip pure membership events
     if (type === StateEvent.RoomMember) return null;
     let body: string;
-    if (latestEvent.isEncrypted()) {
+    if (latestEvent.isDecryptionFailure()) {
       body = 'Encrypted message';
     } else if (type === MessageEvent.Sticker) {
       body = 'Sticker';

src/app/pages/client/direct/Direct.tsx

@@ -270,14 +270,15 @@ export function Direct() {
                   }
                   placeholder="Filter DMs…"
                   variant="Surface"
-                  size="300"
-                  radii="300"
+                  size="400"
+                  radii="400"
+                  before={<Icon size="50" src={Icons.Search} />}
                   after={
                     filterQuery ? (
                       <IconButton
                         onClick={() => setFilterQuery('')}
-                        size="300"
-                        radii="300"
+                        size="400"
+                        radii="Pill"
                         variant="Background"
                         fill="None"
                         aria-label="Clear filter"

src/app/pages/client/home/Home.tsx

@@ -402,14 +402,15 @@ export function Home() {
                   onChange={(e: ChangeEvent<HTMLInputElement>) => setFilterQuery(e.target.value)}
                   placeholder="Filter rooms…"
                   variant="Surface"
-                  size="300"
-                  radii="300"
+                  size="400"
+                  radii="400"
+                  before={<Icon size="50" src={Icons.Search} />}
                   after={
                     filterQuery ? (
                       <IconButton
                         onClick={() => setFilterQuery('')}
-                        size="300"
-                        radii="300"
+                        size="400"
+                        radii="Pill"
                         variant="Background"
                         fill="None"
                         aria-label="Clear filter"