test(lists): improve test coverage and extract list ID parsing

- Extract extractListId to src/lib/extract-list-id.ts with proper tests
- Add json-full/includeRaw test for list timeline
- Add 404 retry tests for getOwnedLists and getListMemberships
- Add tests for skipping invalid list entries and missing owner handling
- Use shared TwitterClientPrivate type from fixtures

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <[email protected]>

src/lib/extract-list-id.ts

@@ -0,0 +1,20 @@
+// ABOUTME: Extract list ID from an X/Twitter list URL.
+// ABOUTME: Returns list ID or null if input is invalid.
+
+const LIST_URL_REGEX = /(?:twitter\.com|x\.com)\/i\/lists\/(\d+)/i;
+const LIST_ID_REGEX = /^\d{5,}$/;
+
+export function extractListId(input: string): string | null {
+  const trimmed = input.trim();
+  if (!trimmed) {
+    return null;
+  }
+  const urlMatch = LIST_URL_REGEX.exec(trimmed);
+  if (urlMatch) {
+    return urlMatch[1];
+  }
+  if (LIST_ID_REGEX.test(trimmed)) {
+    return trimmed;
+  }
+  return null;
+}