feat(data): add WeekReportRepository with tests

src/ClaudeDo.Data/Repositories/WeekReportRepository.cs

@@ -0,0 +1,38 @@
+using ClaudeDo.Data.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace ClaudeDo.Data.Repositories;
+
+public sealed class WeekReportRepository
+{
+    private readonly ClaudeDoDbContext _context;
+
+    public WeekReportRepository(ClaudeDoDbContext context) => _context = context;
+
+    public async Task<WeekReportEntity?> GetByRangeAsync(
+        DateOnly start, DateOnly end, CancellationToken ct = default) =>
+        await _context.WeekReports.AsNoTracking()
+            .FirstOrDefaultAsync(r => r.StartDate == start && r.EndDate == end, ct);
+
+    public async Task UpsertAsync(DateOnly start, DateOnly end, string markdown, CancellationToken ct = default)
+    {
+        var row = await _context.WeekReports
+            .FirstOrDefaultAsync(r => r.StartDate == start && r.EndDate == end, ct);
+        if (row is null)
+        {
+            _context.WeekReports.Add(new WeekReportEntity
+            {
+                StartDate = start,
+                EndDate = end,
+                Markdown = markdown,
+                GeneratedAt = DateTime.UtcNow,
+            });
+        }
+        else
+        {
+            row.Markdown = markdown;
+            row.GeneratedAt = DateTime.UtcNow;
+        }
+        await _context.SaveChangesAsync(ct);
+    }
+}