fix(bugcollect): 修复 V6 no-op 导致 build_id 列缺失引发的 502

V6 迁移原为空操作（SELECT 1），导致 log_issue_events 和 log_sourcemaps
表缺少 build_id 列，服务启动时 Hibernate schema 校验失败并持续重启。

- 重写 V6 为实际 DDL（ALTER TABLE ... ADD COLUMN build_id）
- 新增 V7 幂等修复迁移，使用条件预处理语句，对已有列的部署安全跳过

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

xuqm-bugcollect-service/src/main/resources/db/migration/V6__build_id.sql

@@ -1,4 +1,20 @@
 -- V6: build_id support for multi-build-per-version sourcemap tracking
--- All DDL was applied manually during the initial migration incident.
--- This script is intentionally a no-op to let Flyway record V6 as done.
-SELECT 1;
+--
+-- Adds build_id to log_issue_events and log_sourcemaps so each unique
+-- (appKey, platform, appVersion, buildId, bundleName) combination can
+-- store its own sourcemap file without overwriting sibling builds.
+--
+-- Existing deployments where this column was already added manually:
+-- Flyway will have recorded V6 as done via the old no-op; those databases
+-- have the column already. For any deployment where V6 ran as a no-op
+-- and the column is still missing, run the repair migration V7.
+
+ALTER TABLE log_issue_events
+    ADD COLUMN build_id VARCHAR(32) NULL
+        COMMENT 'Build identifier for sourcemap tracking'
+        AFTER app_version;
+
+ALTER TABLE log_sourcemaps
+    ADD COLUMN build_id VARCHAR(32) NULL
+        COMMENT 'Build identifier for multi-build-per-version sourcemap tracking'
+        AFTER app_version;

xuqm-bugcollect-service/src/main/resources/db/migration/V7__build_id_repair.sql

@@ -0,0 +1,30 @@
+-- V7: repair for deployments where V6 ran as a no-op
+--
+-- On some deployments V6 was recorded as done but contained only SELECT 1,
+-- leaving build_id missing from log_issue_events and log_sourcemaps.
+-- This migration adds the column idempotently using a prepared statement so
+-- it is safe whether the column already exists or not.
+
+SET @_add_lie = IF(
+    NOT EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_schema = DATABASE()
+          AND table_name   = 'log_issue_events'
+          AND column_name  = 'build_id'
+    ),
+    'ALTER TABLE log_issue_events ADD COLUMN build_id VARCHAR(32) NULL COMMENT ''Build identifier for sourcemap tracking'' AFTER app_version',
+    'SELECT 1 /* log_issue_events.build_id already exists */'
+);
+PREPARE _s FROM @_add_lie; EXECUTE _s; DEALLOCATE PREPARE _s;
+
+SET @_add_lsm = IF(
+    NOT EXISTS (
+        SELECT 1 FROM information_schema.columns
+        WHERE table_schema = DATABASE()
+          AND table_name   = 'log_sourcemaps'
+          AND column_name  = 'build_id'
+    ),
+    'ALTER TABLE log_sourcemaps ADD COLUMN build_id VARCHAR(32) NULL COMMENT ''Build identifier for multi-build-per-version sourcemap tracking'' AFTER app_version',
+    'SELECT 1 /* log_sourcemaps.build_id already exists */'
+);
+PREPARE _s FROM @_add_lsm; EXECUTE _s; DEALLOCATE PREPARE _s;