refactor: reorganize directory structure into src/

Move all source code directories into src/ for cleaner project structure:
- pages/, components/, utils/, config/, providers/, types/, lib/, assets/, entrypoints/ → src/
- Use WXT srcDir config to resolve @/ alias to src/
- Update tsconfig, vitest, eslint, tailwind configs
- Remove scattered README.md files from subdirectories
- Update documentation (AGENTS.md, CODING_STANDARDS.md, README.md)
- Fix pre-existing lint error in RouterProvider.tsx

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/pages/QrCode/components/GeneratePanel.tsx

@@ -0,0 +1,57 @@
+import TextInputArea from '@/components/TextInputArea';
+import QrCodePreview from '@/components/QrCodePreview';
+import { useI18n } from '@/utils/chromeI18n';
+import { useQrCodeContext } from '../contexts/QrCodeContext';
+import { Label } from '@/components/ui/label';
+import { cn } from '@/lib/utils';
+
+export default function GeneratePanel() {
+  const { t } = useI18n('qrCode');
+  const { generatorState, setTextToEncode, downloadQrCode, copyQrCode } = useQrCodeContext();
+
+  return (
+    <div className="grid grid-cols-1 md:grid-cols-2 gap-6 w-full items-stretch select-none p-0.5">
+      {/* 左翼：高性能受控输入翼终端 */}
+      <div
+        className={cn(
+          'border border-border rounded-xl bg-card text-card-foreground shadow-sm flex flex-col p-4',
+          'focus-within:ring-1 focus-within:ring-ring focus-within:border-ring',
+        )}
+      >
+        {/* 💡 2. 独立外置标签架（A11y 无障碍对齐）：
+           - 彻底删掉 TextInputArea 上引发崩溃的违规属性。
+           - 改用正统的 <Label />，并注入标准的高度无障碍样式，间距比例极度平滑。
+        */}
+        <div className="flex flex-col space-y-2.5 h-full">
+          <Label className="text-[10px] font-bold text-muted-foreground/90 uppercase tracking-wider select-none pl-0.5">
+            {t('qrCode:urlInputLabel')}
+          </Label>
+
+          <div className="flex-1 min-h-0">
+            <TextInputArea
+              value={generatorState.textToEncode}
+              onChange={setTextToEncode}
+              placeholder={t('qrCode:urlInputPlaceholder')}
+              showCount={true}
+              showClear={true}
+              allowCopy={true}
+              minRows={6}
+              maxRows={12}
+              externalError={generatorState.inputError || undefined}
+              onClear={() => setTextToEncode('')}
+            />
+          </div>
+        </div>
+      </div>
+
+      {/* 右翼：活态二维码高精生成区 */}
+      <div className="flex flex-col h-full">
+        <QrCodePreview
+          qrCodeDataUrl={generatorState.qrCodeDataUrl}
+          onDownload={downloadQrCode}
+          onCopy={copyQrCode}
+        />
+      </div>
+    </div>
+  );
+}