feat: setup db context with initial models

src/FiscalOS.API/Data/AppDbContext.cs

@@ -0,0 +1,38 @@
+namespace FiscalOS.API.Data;
+
+internal sealed class AppDbContext(IOptions<AppDbContextOptions> ctxOptions) : DbContext
+{
+  private const string DataSourceKey = "Data Source=";
+  private readonly AppDbContextOptions _ctxOptions = ctxOptions.Value;
+
+  public DbSet<User> Users => Set<User>();
+  public DbSet<RefreshToken> RefreshTokens => Set<RefreshToken>();
+
+  protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+  {
+    var dbPath = _ctxOptions.GetFullyQualifiedDatabasePath();
+    var dbDirectory = Path.GetDirectoryName(dbPath) ?? throw new InvalidOperationException("Database directory path could not be determined.");
+
+    if (Directory.Exists(dbDirectory) is false)
+    {
+      Directory.CreateDirectory(dbDirectory);
+    }
+
+    var connectionString = $"{DataSourceKey}{dbPath}";
+
+    optionsBuilder.UseSqlite(connectionString);
+  }
+
+  protected override void OnModelCreating(ModelBuilder modelBuilder)
+  {
+    base.OnModelCreating(modelBuilder);
+
+    modelBuilder.Entity<User>()
+      .Property(static u => u.Id)
+      .ValueGeneratedOnAdd();
+
+    modelBuilder.Entity<RefreshToken>()
+      .Property(static t => t.Id)
+      .ValueGeneratedOnAdd();
+  }
+}