docs: add RunAPI sponsor entry to README (en/zh/ja)

Insert sponsor row in all three README locales linking to runapi.co.
EN/JA copy adapted from the Chinese original. Banner center-cropped to
the project standard 1920x798 aspect ratio (preserves the logo and
slogan, trims the decorative top/bottom padding) and saved as JPEG to
keep file size reasonable (1.3 MB PNG -> 206 KB JPEG).

README.md

@@ -140,6 +140,11 @@ Exclusive benefit for CC Switch users: Register via <a href="https://ddshub.shor
 <td>Thanks to ClaudeCN for sponsoring this project! ClaudeCN is an enterprise-grade AI gateway platform operated by a registered company. It delivers high-availability commercial API access to popular models including Claude, GPT, and DeepSeek, and is built around formal enterprise procurement workflows — corporate bank transfers, signed contracts, and full compliance. Register via <a href="https://claudecn.top">this link</a>!</td>
 </tr>
 
+<tr>
+<td width="180"><a href="https://runapi.co"><img src="assets/partners/logos/runapi.jpg" alt="RunAPI" width="150"></a></td>
+<td>Thanks to RunAPI for sponsoring this project! RunAPI is a high-performance and reliable AI model API gateway — one API key gives you access to 150+ mainstream models including OpenAI, Claude, Gemini, DeepSeek, and Grok, with prices as low as 10% of the official rate and excellent stability. It works seamlessly with Claude Code, OpenClaw, and other tools. Exclusive benefit for CC Switch users: register and contact customer support to claim a free ¥14 credit. Register via <a href="https://runapi.co">this link</a>!</td>
+</tr>
+
 </table>
 
 </details>