feat(gemini): add Google Official branding with Gemini icon (#211)

Update Google Gemini preset to match Claude Official styling:
- Rename 'Google' to 'Google Official'
- Add GeminiIcon support in preset selector
- Add custom theme with Google blue (#4285F4) background
- Update PresetTheme type to support 'gemini' icon type

Changes:
- Add GeminiPresetTheme interface
- Add theme config to Google Official preset
- Import and render GeminiIcon in ProviderPresetSelector
- Update PresetTheme icon type to include 'gemini'

src/config/claudeProviderPresets.ts

@@ -14,8 +14,8 @@ export interface TemplateValueConfig {
  * 预设供应商的视觉主题配置
  */
 export interface PresetTheme {
-  /** 图标类型：'claude' | 'codex' | 'generic' */
-  icon?: "claude" | "codex" | "generic";
+  /** 图标类型：'claude' | 'codex' | 'gemini' | 'generic' */
+  icon?: "claude" | "codex" | "gemini" | "generic";
   /** 背景色（选中状态），支持 Tailwind 类名或 hex 颜色 */
   backgroundColor?: string;
   /** 文字色（选中状态），支持 Tailwind 类名或 hex 颜色 */

src/config/geminiProviderPresets.ts

@@ -1,5 +1,17 @@
 import type { ProviderCategory } from "@/types";
 
+/**
+ * Gemini 预设供应商的视觉主题配置
+ */
+export interface GeminiPresetTheme {
+  /** 图标类型：'gemini' | 'generic' */
+  icon?: "gemini" | "generic";
+  /** 背景色（选中状态），支持 hex 颜色 */
+  backgroundColor?: string;
+  /** 文字色（选中状态），支持 hex 颜色 */
+  textColor?: string;
+}
+
 export interface GeminiProviderPreset {
   name: string;
   websiteUrl: string;
@@ -12,11 +24,12 @@ export interface GeminiProviderPreset {
   isPartner?: boolean;
   partnerPromotionKey?: string;
   endpointCandidates?: string[];
+  theme?: GeminiPresetTheme;
 }
 
 export const geminiProviderPresets: GeminiProviderPreset[] = [
   {
-    name: "Google",
+    name: "Google Official",
     websiteUrl: "https://ai.google.dev/",
     apiKeyUrl: "https://aistudio.google.com/apikey",
     settingsConfig: {
@@ -28,6 +41,11 @@ export const geminiProviderPresets: GeminiProviderPreset[] = [
     category: "official",
     partnerPromotionKey: "google-official",
     model: "gemini-2.5-pro",
+    theme: {
+      icon: "gemini",
+      backgroundColor: "#4285F4",
+      textColor: "#FFFFFF",
+    },
   },
   {
     name: "PackyCode",