feat: support rich content in long-form tweets (X Articles)

Add support for extracting rich content from X's long-form tweets,
including embedded code snippets, markdown blocks, quoted tweets,
and other structured content that was previously lost.

Changes:
- Add fieldToggles with withArticleRichContentState to TweetDetail API request
- Implement Draft.js content_state parser (renderContentState) that converts
  blocks and entities to readable markdown format
- Add content_state type definition to GraphqlTweetResult

Supported content:
- Block types: paragraphs, headers, ordered/unordered lists, blockquotes
- Entity types: MARKDOWN (code blocks), DIVIDER, TWEET, LINK, IMAGE

No impact on regular tweets - rich content only adds payload when present.

Includes 20 unit tests for the parser and an opt-in live smoke test.

Co-authored-by: Christian Catalan <[email protected]>

src/lib/twitter-client-types.ts

@@ -130,6 +130,25 @@ export type GraphqlTweetResult = {
             };
           }>;
         }>;
+        /** Draft.js content state for rich article content */
+        content_state?: {
+          blocks: Array<{
+            key: string;
+            type: string;
+            text: string;
+            data?: Record<string, unknown>;
+            entityRanges: Array<{ key: number; offset: number; length: number }>;
+            inlineStyleRanges: Array<{ offset: number; length: number; style: string }>;
+          }>;
+          entityMap: Array<{
+            key: string;
+            value: {
+              type: string;
+              mutability: string;
+              data: Record<string, unknown>;
+            };
+          }>;
+        };
       };
     };
     plain_text?: string;