feat(business): implement block-based content editing and rich text rendering

Introduce a new `BlockEditor` component and upgrade the post/message
rendering system to support rich text segments (images, @mentions,
votes, and post references).

- Implement `BlockEditor` for long-form post creation with image
  embedding support.
- Upgrade `PostContentRenderer` and `SegmentRenderer` to handle
  complex segment types including inline images and block elements.
- Refactor `PostCard` to use segment-based content and image
  signatures for optimized memoization.
- Centralize segment partitioning logic in `segmentUtils.ts` to ensure
  consistent rendering across chat and post modules.
- Update `PostRepository` and `Post` entity to support the new
  `segments` data structure.

src/screens/message/components/ChatScreen/SegmentRenderer.tsx

@@ -39,43 +39,7 @@ const IMAGE_MAX_WIDTH = 200;
 const IMAGE_MAX_HEIGHT = 260;
 const IMAGE_FALLBACK_SIZE = { width: 200, height: 150 };
 
-/** 将非 reply 的 segments 分成：行内文案/@、连续图片组、其它块级（音视频文件等） */
-type ContentChunk =
-  | { kind: 'inline'; parts: MessageSegment[] }
-  | { kind: 'images'; parts: MessageSegment[] }
-  | { kind: 'block'; segment: MessageSegment };
-
-function partitionMessageSegments(segments: MessageSegment[]): ContentChunk[] {
-  const out: ContentChunk[] = [];
-  let inlineBuf: MessageSegment[] = [];
-  const flushInline = () => {
-    if (inlineBuf.length) {
-      out.push({ kind: 'inline', parts: [...inlineBuf] });
-      inlineBuf = [];
-    }
-  };
-
-  for (const s of segments) {
-    if (s.type === 'image') {
-      flushInline();
-      const last = out[out.length - 1];
-      if (last?.kind === 'images') {
-        last.parts.push(s);
-      } else {
-        out.push({ kind: 'images', parts: [s] });
-      }
-    } else if (s.type === 'video' || s.type === 'file' || s.type === 'link' || s.type === 'voice') {
-      flushInline();
-      out.push({ kind: 'block', segment: s });
-    } else if (s.type === 'text' || s.type === 'at' || s.type === 'face') {
-      inlineBuf.push(s);
-    } else {
-      inlineBuf.push(s);
-    }
-  }
-  flushInline();
-  return out;
-}
+import { partitionSegments, type ContentChunk } from '../../../../types/dto';
 
 // Segment 渲染器 Props
 export interface SegmentRendererProps {
@@ -741,7 +705,7 @@ const MessageSegmentsRendererInner: React.FC<{
 
   const replySegment = useMemo(() => segments.find(s => s.type === 'reply'), [segments]);
   const otherSegments = useMemo(() => segments.filter(s => s.type !== 'reply'), [segments]);
-  const chunks = useMemo(() => partitionMessageSegments(otherSegments), [otherSegments]);
+  const chunks = useMemo(() => partitionSegments(otherSegments), [otherSegments]);
 
   const renderProps = useMemo(() => ({
     isMe,

src/screens/message/components/ChatScreen/styles.ts

@@ -296,11 +296,11 @@ export function createChatScreenStyles(colors: AppColors, dynamicStyles?: {
     alignItems: 'flex-start',
   },
   senderName: {
-    fontSize: 14,
-    color: textPrimary,
+    fontSize: 12,
+    color: textSecondary,
     marginBottom: 4,
     marginLeft: 4,
-    fontWeight: '600',
+    fontWeight: '500',
   },
   mySenderName: {
     marginLeft: 0,