Add bulk fill and staggered retrofit at campus/cluster level

Campus level: "Fill All DCs" instantly fills all operational DCs with
selected SKU in one click. "Retrofit Campus" queues a staggered retrofit
with configurable concurrency (1/10%/25%/custom) so only a fraction of
DCs go offline at a time, preserving capacity during the upgrade.

Cluster level: "Fill All DCs" fills across all campuses in one action.

The game engine automatically advances the retrofit queue each tick,
promoting pending DCs as active ones complete.

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

packages/shared/src/types/infrastructure.ts

@@ -18,6 +18,15 @@ export interface Cluster {
 
 export type CampusStatus = 'constructing' | 'operational';
 
+export interface CampusRetrofitQueue {
+  targetSkuId: RackSkuId;
+  maxConcurrent: number;
+  pendingDCIds: string[];
+  activeDCIds: string[];
+  completedDCIds: string[];
+  skippedDCIds: string[];
+}
+
 export interface Campus {
   id: string;
   name: string;
@@ -27,6 +36,7 @@ export interface Campus {
   status: CampusStatus;
   constructionProgress: number;
   constructionTotal: number;
+  retrofitQueue: CampusRetrofitQueue | null;
 }
 
 // --- Data Center ---