feat: improve model/exchange deletion and selection logic

- Add soft delete support for AI models
  * Add deleted field to ai_models table
  * Implement soft delete with sensitive data cleanup
  * Filter deleted records in queries
- Replace browser confirm dialogs with custom styled modals
  * Create DeleteConfirmModal component with Binance theme
  * Add proper warning messages and icons
  * Improve user experience with consistent styling
- Fix duplicate model/exchange display in selection dropdowns
  * Use supportedModels/supportedExchanges for modal selectors
  * Use configuredModels/configuredExchanges for panel display
  * Remove redundant selectableModels/selectableExchanges logic
- Enhance data management
  * Refresh data after deletion operations
  * Proper state cleanup after modal operations
  * Clear sensitive data during soft delete
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: tinkle-community <tinklefund@gmail.com>

db/init.sql

@@ -22,6 +22,7 @@ CREATE TABLE IF NOT EXISTS ai_models (
     api_key TEXT DEFAULT '',
     custom_api_url TEXT DEFAULT '',
     custom_model_name TEXT DEFAULT '',
+    deleted BOOLEAN DEFAULT FALSE,
     created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
     FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE
@@ -167,6 +168,9 @@ INSERT INTO system_config (key, value) VALUES
 ('jwt_secret', '')
 ON CONFLICT (key) DO NOTHING;
 
+-- 数据库迁移：添加 deleted 字段到现有 ai_models 表
+ALTER TABLE ai_models ADD COLUMN IF NOT EXISTS deleted BOOLEAN DEFAULT FALSE;
+
 -- 创建索引
 CREATE INDEX IF NOT EXISTS idx_ai_models_user_id ON ai_models(user_id);
 CREATE INDEX IF NOT EXISTS idx_exchanges_user_id ON exchanges(user_id);