fix(ingress): diagnose missing shared mailbox generated key

共享信箱 insertRaw 取不到 CMINMSGS_ID 时抛出可诊断错误，指明该列必须由库方生成（C-14、Q7）；只改适配代码，不动共享 Schema。

src/main/kotlin/com/gzzn/omms/msgexchange/infra/persistence/jdbc/JdbcCminmsgInboxRepository.kt

@@ -26,6 +26,7 @@ class JdbcCminmsgInboxRepository(
 ) : CminmsgInboxRepository {
 
     override fun insertRaw(rawXml: String): Long =
+        try {
             ds.updateReturningLong(
                 """
                 INSERT INTO cminmsgs (CMINMSGS_CLOB_MSG, CMINMSGS_DATE_RECEIVED, CMINMSGS_DATE_PROCESSED)
@@ -34,6 +35,15 @@ class JdbcCminmsgInboxRepository(
             ) { ps ->
                 ps.setString(1, rawXml)
             }
+        } catch (e: IllegalStateException) {
+            // 只调整适配代码、不碰共享 Schema：把"取不到 generated key"变成可诊断错误，
+            // 指出这是共享信箱 ID 生成方式的前提（C-14、Q7）。
+            throw IllegalStateException(
+                "shared mailbox insert returned no generated CMINMSGS_ID; " +
+                    "the CMINMSGS_ID column must be DB-generated (C-14, Q7)",
+                e,
+            )
+        }
 
     override fun rawOf(msgId: Long): String? =
         ds.queryOne(