docs(readme): fix Kimi Code subscription link and price

The Kimi Code subscription link had drifted across the 5 README
translations: the English README pointed to https://www.kimi.com/kimiplus/sale
at $0.99, while the Japanese, Korean, Russian, and Simplified Chinese
versions pointed to https://www.kimi.com/membership/pricing with a
referral tracking ID, also at $0.99 with an "only this month" qualifier.

Normalized all 5 to the canonical https://www.kimi.com/code at $19,
preserving each language's localized "Kimi Code Subscription" wording.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -137,7 +137,7 @@ Everything below, every feature, every optimization, you don't need to know it.
 
 Even only with following subscriptions, ultrawork will work well (this project is not affiliated, this is just personal recommendation):
 - [ChatGPT Subscription ($20)](https://chatgpt.com/)
-- [Kimi Code Subscription ($0.99) (*only this month)](https://www.kimi.com/kimiplus/sale)
+- [Kimi Code Subscription ($19)](https://www.kimi.com/code)
 - [GLM Coding Plan ($10)](https://z.ai/subscribe)
 - If you are eligible for pay-per-token, using kimi and gemini models won't cost you that much.