feat(ui): replace generic icons with official brand icons

- Add Claude and ChatGPT/Codex official brand SVG icons
- Create BrandIcons component with proper currentColor support
- Update AppSwitcher to use brand icons with Claude's official color (#D97757)
- Icons now dynamically change color based on active state
- Improve brand recognition and visual consistency

src/assets/icons/claude.svg

@@ -0,0 +1 @@
+<?xml version="1.0" standalone="no"?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"><svg t="1757750114641" class="icon" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="1475" xmlns:xlink="http://www.w3.org/1999/xlink" width="200" height="200"><path d="M202.112 678.656l200.64-112.64 3.392-9.792-3.392-5.44h-9.792l-33.6-2.048-114.624-3.072-99.456-4.224-96.384-5.12-24.192-5.12-22.72-29.952 2.304-14.976 20.48-13.696 29.12 2.56 64.576 4.416 96.832 6.72 70.208 4.096 104.064 10.88h16.576l2.304-6.72-5.696-4.16-4.352-4.096-100.224-67.968-108.48-71.744-56.768-41.344-30.72-20.928-15.488-19.584-6.72-42.88 27.84-30.72 37.504 2.56 9.536 2.56 37.952 29.184 81.088 62.784 105.856 77.952 15.488 12.928 6.208-4.352 0.768-3.136L395.264 360l-57.6-104.064-61.44-105.92-27.392-43.904-7.168-26.304c-2.56-10.88-4.48-19.904-4.48-30.976l31.808-43.136L286.592 0l42.304 5.696 17.856 15.488 26.304 60.16 42.624 94.72 66.112 128.896 19.392 38.208 10.24 35.392 3.904 10.88h6.72v-6.208l5.44-72.576 10.048-89.088 9.856-114.688 3.328-32.256 16-38.72 31.808-20.928 24.768 11.904 20.416 29.184-2.88 18.816-12.16 78.72-23.68 123.52-15.552 82.56h9.088l10.304-10.24 41.856-55.552 70.208-87.808 30.976-34.88 36.16-38.464 23.232-18.368h43.904l32.32 48.064-14.464 49.6-45.184 57.28-37.44 48.576-53.76 72.32-33.536 57.856 3.072 4.608 8-0.768 121.408-25.792 65.6-11.904 78.208-13.44 35.392 16.512 3.84 16.832-13.952 34.304-83.648 20.672-98.112 19.648-146.176 34.56-1.792 1.28 2.048 2.56 65.92 6.272 28.096 1.536h68.928l128.384 9.6 33.536 22.144 20.16 27.136-3.392 20.672-51.648 26.304-69.696-16.512-162.688-38.72-55.744-13.952h-7.744v4.672l46.464 45.44 85.184 76.928 106.688 99.2 5.376 24.512-13.632 19.328-14.464-2.048-93.76-70.464-36.16-31.808-81.856-68.928h-5.44v7.232l18.88 27.648 99.648 149.76 5.184 45.952-7.232 14.976-25.856 9.024-28.352-5.12L673.408 856l-60.16-92.16-48.576-82.624-5.952 3.392-28.672 308.544-13.44 15.744-30.976 11.904-25.792-19.648-13.696-31.744 13.696-62.72 16.512-81.92 13.44-65.024 12.16-80.832 7.232-26.88-0.512-1.792-5.952 0.768-60.928 83.648-92.736 125.248-73.344 78.528-17.536 6.976-30.464-15.808 2.816-28.16 17.024-24.96 101.504-129.152 61.184-80 39.552-46.272-0.256-6.72h-2.368L177.6 789.44l-48 6.144-20.736-19.328 2.56-31.744 9.856-10.368 81.088-55.744-0.256 0.256z" p-id="1476" fill="#bfbfbf"></path></svg>

src/components/AppSwitcher.tsx

@@ -1,5 +1,5 @@
 import { AppType } from "../lib/tauri-api";
-import { Terminal, Code2 } from "lucide-react";
+import { ClaudeIcon, CodexIcon } from "./BrandIcons";
 
 interface AppSwitcherProps {
   activeApp: AppType;
@@ -23,8 +23,13 @@ export function AppSwitcher({ activeApp, onSwitch }: AppSwitcherProps) {
             : "text-gray-500 hover:text-gray-900 hover:bg-white/50 dark:text-gray-400 dark:hover:text-gray-100 dark:hover:bg-gray-800/60"
         }`}
       >
-        <Code2 size={16} />
-        <span>Claude Code</span>
+        <ClaudeIcon
+          size={16}
+          className={
+            activeApp === "claude" ? "text-[#D97757] dark:text-[#D97757]" : ""
+          }
+        />
+        <span>Claude</span>
       </button>
 
       <button
@@ -36,7 +41,7 @@ export function AppSwitcher({ activeApp, onSwitch }: AppSwitcherProps) {
             : "text-gray-500 hover:text-gray-900 hover:bg-white/50 dark:text-gray-400 dark:hover:text-gray-100 dark:hover:bg-gray-800/60"
         }`}
       >
-        <Terminal size={16} />
+        <CodexIcon size={16} />
         <span>Codex</span>
       </button>
     </div>