feat(cma): strategy map lane KR delete entry (cma-map-kr-delete-entry-20260916)

- MapNode.vue: hover trash icon per KR row emitting delete-kr (inline SVG, no emoji)

- StrategyLayer.vue / MapCanvas.vue: passthrough + MyDialog second confirm + okrApi.deleteKr + whole-map save

- MapsDialog: single-KR policy hint (keep at least 1 KR per objective)

frontend/src/components/map-canvas/MapCanvasDialogs.vue

@@ -61,7 +61,10 @@
 
       <div class="mc-kr-section">
         <div class="mc-kr-header">
-          <span>关键结果（{{ form.krs.length }}条）</span>
+          <span>
+            关键结果（{{ form.krs.length }}条）
+            <span class="mc-kr-min-hint">每个目标至少保留 1 条</span>
+          </span>
           <span style="display:flex;gap:6px;">
             <el-button size="small" plain @click="autoDivideWeights">⚖️ 自动平分</el-button>
             <el-button size="small" type="primary" plain @click="addKr">+ 添加KR</el-button>
@@ -72,7 +75,7 @@
           <div class="mc-kr-row-top">
             <span class="mc-kr-index">#{{ ki + 1 }}</span>
             <input v-model="kr.name" class="mc-input mc-kr-name" placeholder="KR名称" />
-            <el-button v-if="form.krs.length > 1" size="small" text type="danger" @click="removeKr(ki)">×</el-button>
+            <el-button v-if="form.krs.length > 1" size="small" text type="danger" title="删除该关键结果" @click="removeKr(ki)">×</el-button>
           </div>
           <div class="mc-kr-row-bottom">
             <div class="mc-kr-field">
@@ -937,6 +940,13 @@ function planStatusLabel(s: string): string {
   font-weight: 500;
   color: #606266;
 }
+/* 单条 KR 口径提示（2026-09-16）：不允许删到 0，UI 明示 */
+.mc-kr-min-hint {
+  margin-left: 8px;
+  font-size: 11px;
+  font-weight: 400;
+  color: #909399;
+}
 .mc-kr-row {
   border: 1px solid #e4e7ed;
   border-radius: 6px;

frontend/src/components/strategy-map/MapNode.vue

@@ -51,6 +51,26 @@
           <span class="kr-sub-index">{{ ki + 1 }}</span>
           <span class="kr-sub-name" :title="kr.name">{{ kr.name }}</span>
           <span v-if="kr.target_value" class="kr-sub-target">目标: {{ kr.target_value }}</span>
+          <!-- KR删除入口（2026-09-16）：hover 显示，内联 SVG（Tabler trash），禁用 Emoji -->
+          <button
+            type="button"
+            class="kr-sub-del"
+            :title="canDeleteKr ? '删除该关键结果' : '每个目标至少保留 1 条关键结果'"
+            :aria-label="`删除关键结果 ${kr.name || ki + 1}`"
+            @click.stop="$emit('delete-kr', { index: ki, kr })"
+          >
+            <svg
+              width="12" height="12" viewBox="0 0 24 24" fill="none"
+              stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"
+              aria-hidden="true"
+            >
+              <path d="M4 7h16" />
+              <path d="M10 11v6" />
+              <path d="M14 11v6" />
+              <path d="M5 7l1 12a2 2 0 0 0 2 2h8a2 2 0 0 0 2-2l1-12" />
+              <path d="M9 7V5a1 1 0 0 1 1-1h4a1 1 0 0 1 1 1v2" />
+            </svg>
+          </button>
         </div>
         <div class="kr-sub-bottom">
           <div class="kr-sub-progress-wrap">
@@ -178,6 +198,7 @@ const emit = defineEmits<{
   (e: 'kpi-click', kpiCode: string): void
   (e: 'plan-click'): void
   (e: 'edit-kr', payload: { index: number; kr: any }): void
+  (e: 'delete-kr', payload: { index: number; kr: any }): void
   (e: 'add-kr'): void
 }>()
 
@@ -188,6 +209,17 @@ const hasKrs = computed(() => {
   return props.objective?.krs && Array.isArray(props.objective.krs) && props.objective.krs.length > 0
 })
 
+/**
+ * 是否允许删除 KR。
+ * 口径（2026-09-16）：每个目标至少保留 1 条关键结果——不允许删到 0。
+ * 依据：后端 maps.py `_sync_objectives_krs` 在 `krs` 为空时跳过同步（`if not krs: continue`），
+ * 删到 0 会让 krs 表残留孤儿行；且无 KR 的目标无法计算达成率，与「KR 是 O 的度量单元」口径相悖。
+ * 单条 KR 时按钮仍显示（可发现），点击给出明确提示而不是静默置灰。
+ */
+const canDeleteKr = computed(() => {
+  return Array.isArray(props.objective?.krs) && props.objective.krs.length > 1
+})
+
 const objIcon = computed(() => {
   if (props.objective.icon && props.iconMap) {
     return (props.iconMap as Record<string, string>)[props.objective.icon]
@@ -484,6 +516,35 @@ function getKrProgressText(kr: any): string {
   color: #909399;
   flex-shrink: 0;
 }
+/* KR 删除入口：hover 才显形，避免与 KR 文本拥挤；键盘聚焦时同样可见（可访问性） */
+.kr-sub-del {
+  flex-shrink: 0;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  width: 18px;
+  height: 18px;
+  padding: 0;
+  border: 1px solid transparent;
+  border-radius: 4px;
+  background: transparent;
+  color: #c0c4cc;
+  cursor: pointer;
+  opacity: 0;
+  transition: opacity .15s, color .15s, background .15s, border-color .15s;
+}
+.kr-sub-item:hover .kr-sub-del { opacity: 1; }
+.kr-sub-del:focus-visible {
+  opacity: 1;
+  outline: none;
+  border-color: #f56c6c;
+}
+.kr-sub-del:hover {
+  color: #f56c6c;
+  background: #fef0f0;
+  border-color: #fbc4c4;
+}
+.kr-sub-del:active { transform: scale(0.92); }
 .kr-sub-bottom {
   display: flex;
   align-items: center;

frontend/src/components/strategy-map/StrategyLayer.vue

@@ -53,6 +53,7 @@
               @kpi-click="(code: string) => $emit('kpi-click', code)"
               @plan-click="$emit('show-plan-list', { dimKey: layerKey, idx: index, obj: element })"
               @edit-kr="(p: any) => $emit('edit-kr', { dimKey: layerKey, idx: index, obj: element, ki: p.index, kr: p.kr })"
+              @delete-kr="(p: any) => $emit('delete-kr', { dimKey: layerKey, idx: index, obj: element, ki: p.index, kr: p.kr })"
               @add-kr="$emit('add-kr', { dimKey: layerKey, idx: index, obj: element })"
               />
           </div>
@@ -116,6 +117,7 @@ const emit = defineEmits<{
   (e: 'update:color', val: string): void
   (e: 'update:icon', val: string): void
   (e: 'edit-kr', payload: { dimKey: string; idx: number; obj: any; ki: number; kr: any }): void
+  (e: 'delete-kr', payload: { dimKey: string; idx: number; obj: any; ki: number; kr: any }): void
   (e: 'add-kr', payload: { dimKey: string; idx: number; obj: any }): void
 }>()