feat: StationOverlay 렌더링 최적화 및 스무딩 적용 close #1

- 텍스트(측점/POI) 전 프레임 사전 계산 Map (requestIdleCallback 백그라운드)
- 드론 데이터 이동 평균 스무딩 (smoothFrame ±N프레임)
- 30fps→60fps 프레임 간 선형 보간 (performance.now() 기반)
- EMA(지수이동평균) 표시 위치 스무딩 (α=0.01 기본값)
- 글씨 2배 크기, bold, strokeText 테두리, 배경 박스 제거
- 카메라 파라미터 패널에 smooth/EMA α 슬라이더 추가

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

shared/src/types.ts

@@ -0,0 +1,75 @@
+// Video source types
+export type VideoSourceType = 'local' | 'server';
+
+export type HlsConversionStatus = 'idle' | 'converting' | 'done' | 'error';
+
+export interface VideoMeta {
+  videoId: string;
+  filename: string;
+  size: number;
+  duration: number;
+  fps: number;
+  width: number;
+  height: number;
+  codec: string;
+  hlsStatus: HlsConversionStatus;
+  createdAt: string;
+}
+
+// Annotation types
+export type AnnotationType = 'subtitle' | 'memo';
+
+export interface AnnotationPosition {
+  x: number; // 0-100 percentage
+  y: number; // 0-100 percentage
+}
+
+export interface AnnotationSize {
+  width: number;  // 0-100 percentage
+  height: number; // 0-100 percentage
+}
+
+export interface AnnotationStyle {
+  fontSize?: number;
+  color?: string;
+  backgroundColor?: string;
+}
+
+export interface Annotation {
+  id: string;
+  videoId: string;
+  type: AnnotationType;
+  timeStart: number; // seconds (float)
+  timeEnd: number;   // seconds (float)
+  text: string;
+  position: AnnotationPosition;
+  size: AnnotationSize;
+  style: AnnotationStyle;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export type CreateAnnotationInput = Omit<Annotation, 'id' | 'createdAt' | 'updatedAt'>;
+export type UpdateAnnotationInput = Partial<Omit<Annotation, 'id' | 'videoId' | 'createdAt'>>;
+
+// API response types
+export interface ApiResponse<T> {
+  data?: T;
+  error?: string;
+}
+
+export interface HlsProgressEvent {
+  videoId: string;
+  percent: number;
+  time: number;
+  status: HlsConversionStatus;
+}
+
+// Upload types
+export interface UploadStatus {
+  uploadId: string;
+  filename: string;
+  size: number;
+  uploadedBytes: number;
+  status: 'uploading' | 'complete' | 'error';
+}