refactor(web): extract allocation drag bootstrap

apps/web/src/hooks/useTimelineDrag.ts

@@ -23,6 +23,7 @@ import {
   startAllocationMultiDrag,
   updateAllocationMultiDrag,
 } from "./timelineAllocationMultiDrag.js";
+import { createAllocationDragState } from "./timelineAllocationDragState.js";
 import { buildProjectShiftMutationInput, createProjectDragState } from "./timelineProjectDrag.js";
 import {
   createMultiSelectState,
@@ -682,25 +683,20 @@ export function useTimelineDrag({
 
       // ── Single allocation drag ────────────────────────────────────────────
 
-      const initial: AllocDragState = {
-        isActive: true,
+      const initial = createAllocationDragState<AllocDragState, AllocDragMode, AllocDragScope>({
         mode: opts.mode,
-        scope: opts.scope ?? "allocation",
+        scope: opts.scope,
         allocationId: opts.allocationId,
-        mutationAllocationId: opts.mutationAllocationId ?? opts.allocationId,
+        mutationAllocationId: opts.mutationAllocationId,
         projectId: opts.projectId,
         projectName: opts.projectName,
         resourceId: opts.resourceId,
-        allocationStartDate: opts.allocationStartDate ?? opts.startDate,
-        allocationEndDate: opts.allocationEndDate ?? opts.endDate,
-        originalStartDate: opts.startDate,
-        originalEndDate: opts.endDate,
-        currentStartDate: opts.startDate,
-        currentEndDate: opts.endDate,
+        allocationStartDate: opts.allocationStartDate,
+        allocationEndDate: opts.allocationEndDate,
+        startDate: opts.startDate,
+        endDate: opts.endDate,
         startMouseX: e.clientX,
-        pointerDeltaX: 0,
-        daysDelta: 0,
-      };
+      });
       allocDragRef.current = initial;
       setAllocDragState(initial);
       setAllocationPreviewTarget(e.currentTarget, opts.mode);