refactor: replace flex-full with flex-1 and standardize scrollbar styles

- replace all outdated flex-full utility classes with modern flex-1 across Vue components
- standardize scrollbar hiding by using scrollbar-none utility instead of verbose vendor prefixes
- update order detail page layout and scroll container styling
- add scrollbar-none usage guidelines to AGENTS.md documentation

src/pages/home/components/ChatInputArea/index.vue

@@ -16,7 +16,7 @@
       <div class="min-w-0 flex-1" :class="{ 'pl-[4px]': !isSpeechRecognitionSupported }">
         <textarea ref="textareaRef" v-if="!isVoiceMode" v-model="inputMessage" rows="1" maxlength="300"
           :placeholder="placeholder"
-          class="block h-[22px] max-h-[92px] min-h-[22px] w-full resize-none overflow-x-hidden overflow-y-auto border-0 bg-transparent p-0 text-[14px] leading-[22px] text-[#333] outline-none appearance-none placeholder:text-[#A5AAB4] [scrollbar-width:none] [&::-webkit-scrollbar]:hidden"
+          class="block h-[22px] max-h-[92px] min-h-[22px] w-full resize-none overflow-x-hidden overflow-y-auto border-0 bg-transparent p-0 text-[14px] leading-[22px] text-[#333] outline-none appearance-none placeholder:text-[#A5AAB4] scrollbar-none [&::-webkit-scrollbar]:hidden"
           @input="adjustTextareaHeight" @focus="handleFocus" @blur="handleBlur" @touchstart="handleTouchStart"
           @touchend="handleTouchEnd" />