feat(data): add AppSettings entity, migration, and repository

src/ClaudeDo.Data/Repositories/AppSettingsRepository.cs

@@ -0,0 +1,48 @@
+using ClaudeDo.Data.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace ClaudeDo.Data.Repositories;
+
+public sealed class AppSettingsRepository
+{
+    private readonly ClaudeDoDbContext _context;
+
+    public AppSettingsRepository(ClaudeDoDbContext context) => _context = context;
+
+    public async Task<AppSettingsEntity> GetAsync(CancellationToken ct = default)
+    {
+        var row = await _context.AppSettings.AsNoTracking()
+            .FirstOrDefaultAsync(s => s.Id == AppSettingsEntity.SingletonId, ct);
+        if (row is not null) return row;
+
+        row = new AppSettingsEntity { Id = AppSettingsEntity.SingletonId };
+        _context.AppSettings.Add(row);
+        await _context.SaveChangesAsync(ct);
+        _context.Entry(row).State = EntityState.Detached;
+        return row;
+    }
+
+    public async Task UpdateAsync(AppSettingsEntity updated, CancellationToken ct = default)
+    {
+        var row = await _context.AppSettings
+            .FirstOrDefaultAsync(s => s.Id == AppSettingsEntity.SingletonId, ct);
+        if (row is null)
+        {
+            row = new AppSettingsEntity { Id = AppSettingsEntity.SingletonId };
+            _context.AppSettings.Add(row);
+        }
+
+        row.DefaultClaudeInstructions = updated.DefaultClaudeInstructions ?? string.Empty;
+        row.DefaultModel = string.IsNullOrWhiteSpace(updated.DefaultModel) ? "sonnet" : updated.DefaultModel;
+        row.DefaultMaxTurns = updated.DefaultMaxTurns;
+        row.DefaultPermissionMode = string.IsNullOrWhiteSpace(updated.DefaultPermissionMode)
+            ? "bypassPermissions" : updated.DefaultPermissionMode;
+        row.WorktreeStrategy = string.IsNullOrWhiteSpace(updated.WorktreeStrategy) ? "sibling" : updated.WorktreeStrategy;
+        row.CentralWorktreeRoot = string.IsNullOrWhiteSpace(updated.CentralWorktreeRoot)
+            ? null : updated.CentralWorktreeRoot;
+        row.WorktreeAutoCleanupEnabled = updated.WorktreeAutoCleanupEnabled;
+        row.WorktreeAutoCleanupDays = updated.WorktreeAutoCleanupDays;
+
+        await _context.SaveChangesAsync(ct);
+    }
+}