fix(mileage): 修复车牌多选弹窗手机端右侧溢出与粘贴行为

- 弹窗改为 right-0 锚右，宽度 min(280px, vw-24px)，避免在窄列触发器下右侧溢出
- 移除 onPaste 自动 apply（避免与已输入文本拼接出非预期 token），改为粘贴入框 + 点击「添加」或 Cmd/Ctrl+Enter 确认
- placeholder 文案补充提示

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/modules/mileage/PlateMultiSelect.tsx

@@ -103,23 +103,22 @@ export default function PlateMultiSelect({ allPlates, selected, onChange, placeh
             initial={{ opacity: 0, y: -5 }}
             animate={{ opacity: 1, y: 0 }}
             exit={{ opacity: 0, y: -5 }}
-            className="absolute z-50 left-0 right-0 mt-1 bg-white border border-slate-100 rounded-xl shadow-xl w-[280px] max-w-[calc(100vw-32px)]"
-            style={{ minWidth: '100%' }}
+            className="absolute z-50 right-0 mt-1 bg-white border border-slate-100 rounded-xl shadow-xl"
+            style={{ width: 'min(280px, calc(100vw - 24px))', minWidth: '100%' }}
           >
             <div className="p-2 space-y-2">
               <textarea
                 value={text}
                 onChange={(e) => setText(e.target.value)}
-                onPaste={(e) => {
-                  const pasted = e.clipboardData.getData('text');
-                  if (pasted && /[\s,;，；、]/.test(pasted)) {
-                    e.preventDefault();
-                    apply(text + (text ? ' ' : '') + pasted);
-                  }
-                }}
-                placeholder="粘贴或输入车牌&#10;支持换行/逗号/空格分隔"
+                placeholder="粘贴或输入车牌&#10;支持换行/逗号/空格分隔，回车或点添加确认"
                 className="w-full bg-slate-50 border-none rounded-lg p-2 text-[11px] text-slate-700 outline-none focus:ring-1 focus:ring-blue-500/30 resize-none"
                 rows={3}
+                onKeyDown={(e) => {
+                  if (e.key === 'Enter' && (e.metaKey || e.ctrlKey)) {
+                    e.preventDefault();
+                    apply(text);
+                  }
+                }}
               />
               <div className="flex justify-between items-center">
                 <span className="text-[10px] text-slate-400">已选 <span className="font-bold text-blue-600">{selected.length}</span> 个</span>