fix(backend): Status-Guard fuer Move/Split/Merge auf inaktiven Voelkern

Beim Live-Test im Browser gefunden: move/split/merge liessen sich auch
auf einem bereits DISSOLVED/MERGED-Volk aufrufen und wuerden dort
klaglos durchlaufen - ein Datenintegritaetsproblem, kein reines
UI-Detail. assertActive() wirft jetzt ConflictException (409), wenn
das betroffene Volk (bzw. bei merge: Ziel- und alle zu vereinigenden
Voelker) nicht ACTIVE ist.

Neuer Unit-Test + neuer e2e-Test (dissolve, danach move -> 409).

ApiCore-Backend/src/colonies/colonies.service.ts

@@ -1,4 +1,8 @@
-import { Injectable, NotFoundException } from '@nestjs/common';
+import {
+  ConflictException,
+  Injectable,
+  NotFoundException,
+} from '@nestjs/common';
 import { PrismaService } from '../prisma/prisma.service';
 import { AuditLogService } from '../audit/audit-log.service';
 import { Colony } from '../../generated/prisma';
@@ -27,6 +31,14 @@ export class ColoniesService {
     return colony;
   }
 
+  private assertActive(colony: Colony): void {
+    if (colony.status !== 'ACTIVE') {
+      throw new ConflictException(
+        `Colony ${colony.id} is not active (status: ${colony.status})`,
+      );
+    }
+  }
+
   async create(dto: CreateColonyDto, actingUserId: string): Promise<Colony> {
     const colony = await this.prisma.colony.create({ data: { ...dto } });
     await this.auditLog.record({
@@ -66,6 +78,7 @@ export class ColoniesService {
     actingUserId: string,
   ): Promise<Colony> {
     const before = await this.findById(id);
+    this.assertActive(before);
     const colony = await this.prisma.$transaction(async (tx) => {
       const updated = await tx.colony.update({
         where: { id },
@@ -98,6 +111,7 @@ export class ColoniesService {
     actingUserId: string,
   ): Promise<Colony> {
     const parent = await this.findById(id);
+    this.assertActive(parent);
     const child = await this.prisma.$transaction(async (tx) => {
       const created = await tx.colony.create({
         data: {
@@ -134,6 +148,7 @@ export class ColoniesService {
     actingUserId: string,
   ): Promise<Colony> {
     const survivor = await this.findById(id);
+    this.assertActive(survivor);
     await this.prisma.$transaction(async (tx) => {
       for (const mergedColonyId of dto.mergedColonyIds) {
         const merged = await tx.colony.findUnique({
@@ -142,6 +157,7 @@ export class ColoniesService {
         if (!merged) {
           throw new NotFoundException(`Colony ${mergedColonyId} not found`);
         }
+        this.assertActive(merged);
         await tx.colony.update({
           where: { id: mergedColonyId },
           data: { status: 'MERGED', deactivatedAt: new Date() },