chore: apply oxlint fix-suggestions (unused imports + useless fragments)

Scoped to only `no-unused-vars` and `react/jsx-no-useless-fragment` —
the safe subset of --fix-suggestions. Primary changes:

- Remove unused named imports from statements
- Remove unused default/type imports entirely
- Collapse `<><Single/></>` fragments to `<Single/>`

Verified clean: typecheck + format + lint all green.

packages/app/src/components/message.tsx

@@ -36,7 +36,6 @@ import {
   ChevronDown,
   Check,
   CheckSquare,
-  X,
   Copy,
   TriangleAlertIcon,
   Scissors,
@@ -54,7 +53,7 @@ import Animated, {
 } from "react-native-reanimated";
 import Svg, { Defs, LinearGradient as SvgLinearGradient, Rect, Stop } from "react-native-svg";
 import { createMarkdownStyles } from "@/styles/markdown-styles";
-import { Colors, Fonts } from "@/constants/theme";
+import { Fonts } from "@/constants/theme";
 import * as Clipboard from "expo-clipboard";
 import type { TodoEntry, UserMessageImageAttachment } from "@/types/stream";
 import type { ToolCallDetail } from "@server/server/agent/agent-sdk-types";