feat(core): 데이터 수집 파이프라인 Core 인터페이스 추가 및 Makefile 생성

**Stage 2 (Python → .NET) 진행:**
- ITokenCache.cs: KIS API 토큰 캐싱 추상화
  - 기존 Python sqlite3 로직 → PostgreSQL 기반으로 마이그레이션
  - GetCachedTokenAsync(), SaveTokenAsync(), ClearExpiredTokensAsync()

- IDataCollectionStore.cs: 데이터 수집 저장소 추상화 계약
  - Python data_collection_store_v1.py 계약 매핑
  - UpsertRun/Snapshot/Error, Fetch 메서드
  - CollectionRunRecord, CollectionSnapshotRecord, CollectionErrorRecord DTO
  - CollectionDashboardStateRecord 대시보드 상태 모델

- ICollectionRepository.cs: 웹 API용 데이터 수집 저장소 인터페이스
  - 높은 수준의 추상화 (Dapper + PostgreSQL)
  - SaveRun, UpdateRunStatus, SaveSnapshot, SaveError
  - GetRecentRuns, GetRunSnapshots, GetRunErrors, GetDashboardState
  - GetLatestSnapshotsForTicker

**Stage 3 (Node.js → .NET) 완료:**
- Makefile: npm scripts를 make 타겟으로 변환
  - ops:prepare, ops:validate, ops:data-collect 등 주요 작업
  - dotnet:build, dotnet:run, dotnet:watch 개발 명령어
  - 단계: Python 도구 호출 유지 (Phase 2 완료까지)

**다음 단계:**
- CollectionRepository PostgreSQL 구현체 (Dapper)
- TokenCache PostgreSQL 구현체
- DataCollectionStore PostgreSQL 구현체 (필요시)
- Program.cs DI 등록
- Web API Collection 엔드포인트 추가

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/dotnet/QuantEngine.Core/Interfaces/IDataCollectionStore.cs

@@ -0,0 +1,95 @@
+namespace QuantEngine.Core.Interfaces;
+
+/// <summary>
+/// Data collection storage abstraction layer.
+/// Maps Python data_collection_store_v1.py contracts to .NET.
+/// Supports PostgreSQL backend for production.
+/// </summary>
+public interface IDataCollectionStore
+{
+    /// <summary>
+    /// Initialize storage tables and schema (idempotent).
+    /// </summary>
+    Task InitializeAsync();
+
+    /// <summary>
+    /// Insert or update collection run record.
+    /// </summary>
+    Task UpsertRunAsync(CollectionRunRecord run);
+
+    /// <summary>
+    /// Insert collection snapshot record.
+    /// </summary>
+    Task UpsertSnapshotAsync(CollectionSnapshotRecord snapshot);
+
+    /// <summary>
+    /// Append error record from collection attempt.
+    /// </summary>
+    Task AppendErrorAsync(CollectionErrorRecord error);
+
+    /// <summary>
+    /// Fetch recent collection runs for dashboard.
+    /// </summary>
+    /// <param name="limit">Max number of runs to return</param>
+    Task<List<CollectionRunRecord>> FetchRecentRunsAsync(int limit = 20);
+
+    /// <summary>
+    /// Fetch latest snapshots for a ticker/dataset combination.
+    /// </summary>
+    Task<List<CollectionSnapshotRecord>> FetchLatestSnapshotsAsync(string ticker, string? datasetName = null, int limit = 10);
+
+    /// <summary>
+    /// Get collection pipeline dashboard state.
+    /// </summary>
+    Task<CollectionDashboardStateRecord> GetDashboardStateAsync();
+}
+
+/// <summary>
+/// Collection run record (maps Python CollectionRun).
+/// </summary>
+public record CollectionRunRecord(
+    string RunId,
+    string Status,
+    string StartedAt,
+    string? FinishedAt = null,
+    int? TotalSnapshots = null,
+    int? TotalErrors = null,
+    string UpdatedAt = ""
+);
+
+/// <summary>
+/// Collection snapshot record (maps Python CollectionSnapshot).
+/// </summary>
+public record CollectionSnapshotRecord(
+    string RunId,
+    string DatasetName,
+    string Ticker,
+    string SourceName,
+    string PayloadJson,
+    string CapturedAt,
+    string CreatedAt = ""
+);
+
+/// <summary>
+/// Collection error record (maps Python CollectionSourceError).
+/// </summary>
+public record CollectionErrorRecord(
+    string RunId,
+    string SourceName,
+    string ErrorKind,
+    string ErrorMessage,
+    string Ticker = "",
+    string CreatedAt = ""
+);
+
+/// <summary>
+/// Dashboard state summary.
+/// </summary>
+public record CollectionDashboardStateRecord(
+    string? LastRunId,
+    string? LastRunStatus,
+    string? LastFinishedAt,
+    int TotalSnapshots,
+    int TotalErrors,
+    List<CollectionErrorRecord> RecentErrors
+);