feat: enhance provider configuration UX with custom URL support and API key links

- Add custom base URL input for custom providers
  - New "Request URL" field appears only in custom mode
  - Automatically syncs with ANTHROPIC_BASE_URL in config
  - Includes helpful amber-styled hint about Claude API compatibility

- Add "Get API Key" links for non-official providers
  - Shows for cn_official, aggregator, and third_party categories
  - Links point to provider's official website
  - Styled as subtle helper text (text-xs, gray-500)
  - Positioned closely under API key input for better visual grouping

- Improve UI consistency and hints
  - Unify all hint boxes to use amber color scheme (amber-50/amber-200/amber-600)
  - Update model placeholders to latest versions (GLM-4.5, GLM-4.5-Air)
  - Simplify provider names (remove version numbers and redundant text)

- Update provider presets
  - GLM models: glm-4-plus → GLM-4.5, glm-4-flash → GLM-4.5-Air
  - Qwen models: qwen-coder-turbo → qwen3-coder-plus
  - Cleaner naming: "Claude官方登录" → "Claude官方", "DeepSeek v3.1" → "DeepSeek"

- Fix Kimi model selector behavior
  - Remove API key requirement for displaying selector
  - Avoid showing duplicate model input fields for Kimi preset
  - Improve hint message clarity

src/components/ProviderForm/KimiModelSelector.tsx

@@ -172,9 +172,9 @@ const KimiModelSelector: React.FC<KimiModelSelectorProps> = ({
       </div>
 
       {!apiKey.trim() && (
-        <div className="p-3 bg-gray-100 border border-gray-200 rounded-lg">
-          <p className="text-xs text-gray-500">
-            📝 请先填写 API Key（格式：sk-xxx-api-key-here）以获取可用模型列表
+        <div className="p-3 bg-amber-50 border border-amber-200 rounded-lg">
+          <p className="text-xs text-amber-600">
+            💡 填写 API Key 后将自动获取可用模型列表
           </p>
         </div>
       )}