fix: Spring 多构造器类显式 @Autowired 标注 + V95 迁移兼容 MySQL 8.4

- CapacityPlanService / ExternalCallMetricsRecorder / ZiniaoClientImpl：
  双构造器（生产 + 测试入口）导致 Spring 6 不自动推断构造器注入，
  启动报 'No default constructor found'；生产构造器显式加 @Autowired
- V95：shop_key 列 V85 建表时已有，原 ADD COLUMN shop_key 会报
  duplicate column；MySQL 8.4 不支持 ADD COLUMN IF NOT EXISTS，改
  information_schema 动态 SQL；shop_key 缩到 VARCHAR(255) 以容纳
  (shop_key, business_date) 唯一键（1000 在 utf8mb4 下超 3072 字节
  索引上限）；删除多余行改为单表 DELETE

backend-java/src/main/java/com/nanri/aiimage/config/CapacityPlanService.java

@@ -1,6 +1,7 @@
 package com.nanri.aiimage.config;
 
 import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.CommandLineRunner;
 import org.springframework.stereotype.Component;
 
@@ -20,7 +21,8 @@ public class CapacityPlanService implements CommandLineRunner {
     private final CapacityPlanProperties properties;
     private final long machineMaxMemoryBytes;
 
-    /** 供测试注入机器内存字节数；生产构造时取 Runtime.maxMemory()。 */
+    /** 生产构造：测试用双参构造器存在，Spring 不会自动推断，必须显式 @Autowired。 */
+    @Autowired
     public CapacityPlanService(CapacityPlanProperties properties) {
         this(properties, maxMemoryBytes());
     }

backend-java/src/main/java/com/nanri/aiimage/metrics/ExternalCallMetricsRecorder.java

@@ -4,6 +4,7 @@ import io.micrometer.core.instrument.DistributionSummary;
 import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.Timer;
 import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.client.ClientHttpRequestInterceptor;
 import org.springframework.http.client.ClientHttpResponse;
 import org.springframework.stereotype.Component;
@@ -28,6 +29,8 @@ public class ExternalCallMetricsRecorder {
 
     private final ObjectProvider<MeterRegistry> meterRegistryProvider;
 
+    /** 生产构造：测试用 MeterRegistry 构造器存在，Spring 不会自动推断，必须显式 @Autowired。 */
+    @Autowired
     public ExternalCallMetricsRecorder(ObjectProvider<MeterRegistry> meterRegistryProvider) {
         this.meterRegistryProvider = meterRegistryProvider;
     }

backend-java/src/main/java/com/nanri/aiimage/modules/ziniao/client/ZiniaoClientImpl.java

@@ -6,6 +6,7 @@ import com.nanri.aiimage.common.exception.BusinessException;
 import com.nanri.aiimage.config.ZiniaoProperties;
 import com.nanri.aiimage.modules.ziniao.model.cache.ZiniaoShopCacheDto;
 import com.nanri.aiimage.modules.ziniao.model.vo.ZiniaoStaffItemVo;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.HttpStatusCode;
 import org.springframework.http.MediaType;
 import org.springframework.http.client.SimpleClientHttpRequestFactory;
@@ -26,6 +27,8 @@ public class ZiniaoClientImpl implements ZiniaoClient {
     private final ObjectMapper objectMapper;
     private final com.nanri.aiimage.metrics.ExternalCallMetricsRecorder externalCallMetrics;
 
+    /** 生产构造：双构造器下 Spring 不会自动推断，必须显式 @Autowired。 */
+    @Autowired
     public ZiniaoClientImpl(ZiniaoProperties ziniaoProperties, ObjectMapper objectMapper) {
         this(ziniaoProperties, objectMapper, null);
     }