README: the new TranscriptFetch logo (#1)

The five-bar mark on its blue tile, the same artwork as the app icon on
transcriptfetch.com, replacing the old three-bar mark (or adding the logo
where the README had none). Linked by absolute URL so it also renders on
npm and PyPI.


Claude-Session: https://claude.ai/code/session_01MPXfTsFDYZxfzGbbosZu1m

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

Author: Transcript-Fetch-Admin

README.md

@@ -1,3 +1,7 @@
+<p align="center">
+  <img src="https://raw.githubusercontent.com/TranscriptFetch/transcript-api-node/main/assets/logo.png" alt="TranscriptFetch" width="84" height="84" />
+</p>
+
 # TranscriptFetch Node.js SDK
 
 The official Node.js / TypeScript client for the [TranscriptFetch API](https://transcriptfetch.com). Fetch transcripts as clean, typed data, with built-in retries, idempotency, and a typed error hierarchy.