A-7（検索・フィルタ）の実装が完了しました。

実装内容:

テキスト検索: 圃場名・住所で部分一致検索（リアルタイムフィルタリング、検索アイコン付き）
作物フィルタ: ドロップダウンで特定作物に絞り込み
未割当トグル: チェックボックスで未割当の圃場のみ表示
件数表示: フィルタ適用中は 5/39件 のように表示
チェックボックス全選択もフィルタ結果に連動
http://localhost:3000/allocation で確認できます。

frontend/src/app/allocation/page.tsx

@@ -4,7 +4,7 @@ import { useState, useEffect, useMemo } from 'react';
 import { api } from '@/lib/api';
 import { Field, Crop, Plan } from '@/types';
 import Navbar from '@/components/Navbar';
-import { Menu, X, BarChart3, ChevronRight, ChevronDown, ArrowUp, ArrowDown, Copy, Settings, Trash2, CheckSquare } from 'lucide-react';
+import { Menu, X, BarChart3, ChevronRight, ChevronDown, ArrowUp, ArrowDown, Copy, Settings, Trash2, CheckSquare, Search } from 'lucide-react';
 
 interface SummaryItem {
   cropId: number;
@@ -39,6 +39,9 @@ export default function AllocationPage() {
   const [bulkCropId, setBulkCropId] = useState<number | 0>(0);
   const [bulkVarietyId, setBulkVarietyId] = useState<number | 0>(0);
   const [bulkUpdating, setBulkUpdating] = useState(false);
+  const [searchText, setSearchText] = useState('');
+  const [filterCropId, setFilterCropId] = useState<number | 0>(0);
+  const [filterUnassigned, setFilterUnassigned] = useState(false);
 
   useEffect(() => {
     fetchData();
@@ -143,6 +146,35 @@ export default function AllocationPage() {
     return sorted;
   }, [fields, sortType, plans]);
 
+  const filteredFields = useMemo(() => {
+    let result = sortedFields;
+
+    if (searchText) {
+      const query = searchText.toLowerCase();
+      result = result.filter(
+        (f) =>
+          f.name.toLowerCase().includes(query) ||
+          (f.address && f.address.toLowerCase().includes(query))
+      );
+    }
+
+    if (filterCropId) {
+      result = result.filter((f) => {
+        const plan = plans.find((p) => p.field === f.id);
+        return plan?.crop === filterCropId;
+      });
+    }
+
+    if (filterUnassigned) {
+      result = result.filter((f) => {
+        const plan = plans.find((p) => p.field === f.id);
+        return !plan?.crop;
+      });
+    }
+
+    return result;
+  }, [sortedFields, searchText, filterCropId, filterUnassigned, plans]);
+
   const groupOptions = useMemo(() => {
     const groups = new Set<string>();
     fields.forEach(f => {
@@ -335,10 +367,10 @@ export default function AllocationPage() {
   };
 
   const toggleAllFields = () => {
-    if (selectedFields.size === sortedFields.length) {
+    if (selectedFields.size === filteredFields.length) {
       setSelectedFields(new Set());
     } else {
-      setSelectedFields(new Set(sortedFields.map((f) => f.id)));
+      setSelectedFields(new Set(filteredFields.map((f) => f.id)));
     }
   };
 
@@ -565,7 +597,51 @@ export default function AllocationPage() {
               </div>
             </div>
 
-            {sortedFields.length === 0 ? (
+            {/* 検索・フィルタバー */}
+            <div className="mb-4 flex flex-wrap items-center gap-2">
+              <div className="relative flex-1 min-w-[200px] max-w-sm">
+                <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-gray-400" />
+                <input
+                  type="text"
+                  value={searchText}
+                  onChange={(e) => setSearchText(e.target.value)}
+                  placeholder="圃場名・住所で検索..."
+                  className="w-full pl-9 pr-3 py-2 border border-gray-300 rounded-md text-sm focus:outline-none focus:ring-2 focus:ring-green-500"
+                />
+              </div>
+              <select
+                value={filterCropId || ''}
+                onChange={(e) => { setFilterCropId(parseInt(e.target.value) || 0); setFilterUnassigned(false); }}
+                className="px-3 py-2 border border-gray-300 rounded-md text-sm focus:outline-none focus:ring-2 focus:ring-green-500"
+              >
+                <option value="">全作物</option>
+                {crops.map((crop) => (
+                  <option key={crop.id} value={crop.id}>{crop.name}</option>
+                ))}
+              </select>
+              <label className="flex items-center gap-1.5 text-sm text-gray-700 cursor-pointer">
+                <input
+                  type="checkbox"
+                  checked={filterUnassigned}
+                  onChange={(e) => { setFilterUnassigned(e.target.checked); if (e.target.checked) setFilterCropId(0); }}
+                  className="rounded border-gray-300 text-green-600 focus:ring-green-500"
+                />
+                未割当のみ
+              </label>
+              {(searchText || filterCropId || filterUnassigned) && (
+                <span className="text-sm text-gray-500">
+                  {filteredFields.length}/{fields.length}件
+                </span>
+              )}
+            </div>
+
+            {filteredFields.length === 0 && fields.length > 0 ? (
+              <div className="bg-white rounded-lg shadow p-8 text-center">
+                <p className="text-gray-500">
+                  条件に一致する圃場がありません。
+                </p>
+              </div>
+            ) : sortedFields.length === 0 ? (
               <div className="bg-white rounded-lg shadow p-8 text-center">
                 <p className="text-gray-500">
                   圃場データがありません。インポートを実行してください。
@@ -631,7 +707,7 @@ export default function AllocationPage() {
                           <th className="px-2 py-3 w-10">
                             <input
                               type="checkbox"
-                              checked={selectedFields.size === sortedFields.length && sortedFields.length > 0}
+                              checked={selectedFields.size === filteredFields.length && filteredFields.length > 0}
                               onChange={toggleAllFields}
                               className="rounded border-gray-300 text-green-600 focus:ring-green-500"
                             />
@@ -662,7 +738,7 @@ export default function AllocationPage() {
                         </tr>
                       </thead>
                       <tbody className="bg-white divide-y divide-gray-200">
-                        {sortedFields.map((field, index) => {
+                        {filteredFields.map((field, index) => {
                           const plan = getPlanForField(field.id);
                           const selectedCropId = plan?.crop || 0;
                           const selectedVarietyId = plan?.variety || 0;
@@ -690,7 +766,7 @@ export default function AllocationPage() {
                                     </button>
                                     <button
                                       onClick={() => moveDown(index)}
-                                      disabled={index === sortedFields.length - 1 || saving === field.id}
+                                      disabled={index === filteredFields.length - 1 || saving === field.id}
                                       className="p-1 hover:bg-gray-100 rounded disabled:opacity-30"
                                       title="下へ移動"
                                     >