feat: init fitness-coach (backend + miniprogram)

- backend: NestJS service with exercise/plan data
- miniprogram: WeChat mini program client
- exclude node_modules, dist, runtime data-store, local env

backend/src/exercises/dto/query-exercises.dto.ts

@@ -0,0 +1,49 @@
+import { IsOptional, IsString, IsInt, Min, Max, IsIn } from 'class-validator';
+import { Type } from 'class-transformer';
+
+export class QueryExercisesDto {
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  @Min(1)
+  page = 1;
+
+  @IsOptional()
+  @Type(() => Number)
+  @IsInt()
+  @Min(1)
+  @Max(50)
+  pageSize = 20;
+
+  @IsOptional()
+  @IsString()
+  bodyPart?: string;
+
+  @IsOptional()
+  @IsString()
+  equipment?: string;
+
+  @IsOptional()
+  @IsString()
+  target?: string;
+
+  @IsOptional()
+  @IsString()
+  muscleGroup?: string;
+
+  @IsOptional()
+  @IsIn(['strength', 'cardio', 'flexibility'])
+  type?: 'strength' | 'cardio' | 'flexibility';
+
+  @IsOptional()
+  @IsString()
+  secondary?: string;
+
+  @IsOptional()
+  @IsString()
+  q?: string;
+
+  @IsOptional()
+  @IsIn(['default', 'name'])
+  sort?: 'default' | 'name' = 'default';
+}