🐛 Fix: align AIDP knowledge base name validation

[cj2026-bit]

Problem

AIDP introduced validation for knowledge base names, but Nexent did not synchronize the frontend validation rules.

The name must:

• Start with a Chinese character or an English letter
• Contain only Chinese characters, English letters, digits, or underscores afterward
• Be between 1 and 256 characters long

The previous frontend regex also contained a typo: 1-z should be a-z.

Fix

• Corrected the knowledge base name regex
• Added validation to the create and update knowledge base forms
• Added detailed Chinese and English validation messages

Verification