feat(ui): add icon picker, color picker and provider icon components

Implement comprehensive icon selection system for provider customization:

## New Components

### ProviderIcon (src/components/ProviderIcon.tsx)
- Render SVG icons by name with automatic fallback
- Display provider initials when icon not found
- Support custom sizing via size prop
- Use dangerouslySetInnerHTML for inline SVG rendering

### IconPicker (src/components/IconPicker.tsx)
- Grid-based icon selection with visual preview
- Real-time search filtering by name and keywords
- Integration with icon metadata for display names
- Responsive grid layout (6-10 columns based on screen)

### ColorPicker (src/components/ColorPicker.tsx)
- 12 preset colors for quick selection
- Native color input for custom color picking
- Hex input field for precise color entry
- Visual feedback for selected color state

## Icon Assets (src/icons/extracted/)
- 38 high-quality SVG icons for AI providers and platforms
- Includes: OpenAI, Claude, DeepSeek, Qwen, Kimi, Gemini, etc.
- Cloud platforms: AWS, Azure, Google Cloud, Cloudflare
- Auto-generated index.ts with getIcon/hasIcon helpers
- Metadata system with searchable keywords per icon

## Build Scripts
- scripts/extract-icons.js: Extract icons from simple-icons
- scripts/generate-icon-index.js: Generate TypeScript index file

src/components/IconPicker.tsx

@@ -0,0 +1,85 @@
+import React, { useState, useMemo } from "react";
+import { useTranslation } from "react-i18next";
+import { Input } from "@/components/ui/input";
+import { Label } from "@/components/ui/label";
+import { ProviderIcon } from "./ProviderIcon";
+import { iconList } from "@/icons/extracted";
+import { searchIcons, getIconMetadata } from "@/icons/extracted/metadata";
+import { cn } from "@/lib/utils";
+
+interface IconPickerProps {
+  value?: string; // 当前选中的图标
+  onValueChange: (icon: string) => void; // 选择回调
+  color?: string; // 预览颜色
+}
+
+export const IconPicker: React.FC<IconPickerProps> = ({
+  value,
+  onValueChange,
+}) => {
+  const { t } = useTranslation();
+  const [searchQuery, setSearchQuery] = useState("");
+
+  // 过滤图标列表
+  const filteredIcons = useMemo(() => {
+    if (!searchQuery) return iconList;
+    return searchIcons(searchQuery);
+  }, [searchQuery]);
+
+  return (
+    <div className="space-y-4">
+      <div>
+        <Label htmlFor="icon-search">
+          {t("iconPicker.search", { defaultValue: "搜索图标" })}
+        </Label>
+        <Input
+          id="icon-search"
+          type="text"
+          placeholder={t("iconPicker.searchPlaceholder", {
+            defaultValue: "输入图标名称...",
+          })}
+          value={searchQuery}
+          onChange={(e) => setSearchQuery(e.target.value)}
+          className="mt-2"
+        />
+      </div>
+
+      <div className="max-h-[65vh] overflow-y-auto pr-1">
+        <div className="grid grid-cols-6 sm:grid-cols-8 lg:grid-cols-10 gap-2">
+          {filteredIcons.map((iconName) => {
+            const meta = getIconMetadata(iconName);
+            const isSelected = value === iconName;
+
+            return (
+              <button
+                key={iconName}
+                type="button"
+                onClick={() => onValueChange(iconName)}
+                className={cn(
+                  "flex flex-col items-center gap-1 p-3 rounded-lg",
+                  "border-2 transition-all duration-200",
+                  "hover:bg-accent hover:border-primary/50",
+                  isSelected
+                    ? "border-primary bg-primary/10"
+                    : "border-transparent",
+                )}
+                title={meta?.displayName || iconName}
+              >
+                <ProviderIcon icon={iconName} name={iconName} size={32} />
+                <span className="text-xs text-muted-foreground truncate w-full text-center">
+                  {meta?.displayName || iconName}
+                </span>
+              </button>
+            );
+          })}
+        </div>
+      </div>
+
+      {filteredIcons.length === 0 && (
+        <div className="text-center py-8 text-muted-foreground">
+          {t("iconPicker.noResults", { defaultValue: "未找到匹配的图标" })}
+        </div>
+      )}
+    </div>
+  );
+};