Sets up calendar package with core infrastructure

Adds core calendar package components including:
- Base services for events, resources, and settings
- Calendar app and orchestrator
- Build and bundling configuration
- IndexedDB storage setup

Prepares foundational architecture for calendar functionality

packages/calendar/src/managers/EdgeScrollManager.ts

@@ -0,0 +1,140 @@
+/**
+ * EdgeScrollManager - Auto-scroll when dragging near viewport edges
+ *
+ * 2-zone system:
+ * - Inner zone (0-50px): Fast scroll (640 px/sec)
+ * - Outer zone (50-100px): Slow scroll (140 px/sec)
+ */
+
+import { IEventBus } from '../types/CalendarTypes';
+import { CoreEvents } from '../constants/CoreEvents';
+
+export class EdgeScrollManager {
+  private scrollableContent: HTMLElement | null = null;
+  private timeGrid: HTMLElement | null = null;
+  private draggedElement: HTMLElement | null = null;
+  private scrollRAF: number | null = null;
+  private mouseY = 0;
+  private isDragging = false;
+  private isScrolling = false;
+  private lastTs = 0;
+  private rect: DOMRect | null = null;
+  private initialScrollTop = 0;
+
+  private readonly OUTER_ZONE = 100;
+  private readonly INNER_ZONE = 50;
+  private readonly SLOW_SPEED = 140;
+  private readonly FAST_SPEED = 640;
+
+  constructor(private eventBus: IEventBus) {
+    this.subscribeToEvents();
+    document.addEventListener('pointermove', this.trackMouse);
+  }
+
+  init(scrollableContent: HTMLElement): void {
+    this.scrollableContent = scrollableContent;
+    this.timeGrid = scrollableContent.querySelector('swp-time-grid');
+    this.scrollableContent.style.scrollBehavior = 'auto';
+  }
+
+  private trackMouse = (e: PointerEvent): void => {
+    if (this.isDragging) {
+      this.mouseY = e.clientY;
+    }
+  };
+
+  private subscribeToEvents(): void {
+    this.eventBus.on(CoreEvents.EVENT_DRAG_START, (event: Event) => {
+      const payload = (event as CustomEvent).detail;
+      this.draggedElement = payload.element;
+      this.startDrag();
+    });
+
+    this.eventBus.on(CoreEvents.EVENT_DRAG_END, () => this.stopDrag());
+    this.eventBus.on(CoreEvents.EVENT_DRAG_CANCEL, () => this.stopDrag());
+  }
+
+  private startDrag(): void {
+    this.isDragging = true;
+    this.isScrolling = false;
+    this.lastTs = 0;
+    this.initialScrollTop = this.scrollableContent?.scrollTop ?? 0;
+
+    if (this.scrollRAF === null) {
+      this.scrollRAF = requestAnimationFrame(this.scrollTick);
+    }
+  }
+
+  private stopDrag(): void {
+    this.isDragging = false;
+    this.setScrollingState(false);
+
+    if (this.scrollRAF !== null) {
+      cancelAnimationFrame(this.scrollRAF);
+      this.scrollRAF = null;
+    }
+
+    this.rect = null;
+    this.lastTs = 0;
+    this.initialScrollTop = 0;
+  }
+
+  private calculateVelocity(): number {
+    if (!this.rect) return 0;
+
+    const distTop = this.mouseY - this.rect.top;
+    const distBot = this.rect.bottom - this.mouseY;
+
+    if (distTop < this.INNER_ZONE) return -this.FAST_SPEED;
+    if (distTop < this.OUTER_ZONE) return -this.SLOW_SPEED;
+    if (distBot < this.INNER_ZONE) return this.FAST_SPEED;
+    if (distBot < this.OUTER_ZONE) return this.SLOW_SPEED;
+
+    return 0;
+  }
+
+  private isAtBoundary(velocity: number): boolean {
+    if (!this.scrollableContent || !this.timeGrid || !this.draggedElement) return false;
+
+    const atTop = this.scrollableContent.scrollTop <= 0 && velocity < 0;
+    const atBottom = velocity > 0 &&
+      this.draggedElement.getBoundingClientRect().bottom >=
+      this.timeGrid.getBoundingClientRect().bottom;
+
+    return atTop || atBottom;
+  }
+
+  private setScrollingState(scrolling: boolean): void {
+    if (this.isScrolling === scrolling) return;
+
+    this.isScrolling = scrolling;
+    if (scrolling) {
+      this.eventBus.emit(CoreEvents.EDGE_SCROLL_STARTED, {});
+    } else {
+      this.initialScrollTop = this.scrollableContent?.scrollTop ?? 0;
+      this.eventBus.emit(CoreEvents.EDGE_SCROLL_STOPPED, {});
+    }
+  }
+
+  private scrollTick = (ts: number): void => {
+    if (!this.isDragging || !this.scrollableContent) return;
+
+    const dt = this.lastTs ? (ts - this.lastTs) / 1000 : 0;
+    this.lastTs = ts;
+    this.rect ??= this.scrollableContent.getBoundingClientRect();
+
+    const velocity = this.calculateVelocity();
+
+    if (velocity !== 0 && !this.isAtBoundary(velocity)) {
+      const scrollDelta = velocity * dt;
+      this.scrollableContent.scrollTop += scrollDelta;
+      this.rect = null;
+      this.eventBus.emit(CoreEvents.EDGE_SCROLL_TICK, { scrollDelta });
+      this.setScrollingState(true);
+    } else {
+      this.setScrollingState(false);
+    }
+
+    this.scrollRAF = requestAnimationFrame(this.scrollTick);
+  };
+}