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/JsonTools/JsonDiffInput.tsx

@@ -0,0 +1,44 @@
+import React from 'react';
+import TextInputArea from '@/components/TextInputArea';
+import { cn } from '@/lib/utils';
+
+// 💡 核心修复：使用 Omit<..., 'onChange'> 强行挖掉原生的 onChange 签名
+// 这样我们自定义的 (value: string) => void 就能独占鳌头，彻底消灭 TS2430 接口冲突！
+export interface JsonDiffInputProps extends Omit<React.HTMLAttributes<HTMLDivElement>, 'onChange'> {
+  label: string;
+  placeholder: string;
+  value: string;
+  onChange: (value: string) => void;
+  error?: string | null;
+  minRows?: number;
+}
+
+export default function JsonDiffInput({
+  label,
+  placeholder,
+  value,
+  onChange,
+  error,
+  minRows = 10,
+  className,
+  ...props
+}: JsonDiffInputProps) {
+  return (
+    <div className={cn('flex-1 min-w-0 flex flex-col', className)} {...props}>
+      <span className="block mb-2 text-[10px] font-bold tracking-wide text-muted-foreground/80 uppercase select-none px-0.5">
+        {label}
+      </span>
+
+      <TextInputArea
+        value={value}
+        onChange={onChange}
+        placeholder={placeholder}
+        minRows={minRows}
+        maxRows={16}
+        externalError={error ?? undefined}
+        showClear={true}
+        allowCopy={true}
+      />
+    </div>
+  );
+}