[CLAUDE] Tests Phase 2: Code generator format + sequence tests (SQLite in-memory)

Phase 2 — chống regression code generator. 17 test mới integration với
DB thật (SQLite in-memory) tổng cộng 71 test pass < 3 giây.

Test project:
- tests/SolutionErp.Infrastructure.Tests/ (xUnit + FluentAssertions + EF SQLite 10)
- ProjectReference SolutionErp.Infrastructure (transitively get Application + Domain)
- Added vào SolutionErp.slnx

Test fixtures:
- Common/SqliteDbFixture.cs:
  - SQLite ":memory:" + shared connection + EnsureCreated() từ DbContext model
  - TestApplicationDbContext subclass — override OnModelCreating replace
    'nvarchar(max)' → 'TEXT' (SQLite không support max keyword)
  - FixedDateTime stub IDateTime cho deterministic year boundary test

Test files:
- Services/ContractCodeGeneratorTests.cs (10 test):
  - Format per ContractType (5 type × Project scope) — RG-001 spec
  - Framework HĐ (NguyenTacNCC + NguyenTacDV) → year scope thay vì project
  - Sequence increment per prefix (3 calls → /01, /02, /03)
  - Different prefixes (project / supplier) → independent sequences
  - Year change (2026 → 2027) → reset sequence vì prefix khác
  - PersistsSequenceRow LastSeq verification
- Services/PurchaseEvaluationCodeGeneratorTests.cs (7 test):
  - Format A/B (DuyetNcc → 'A', DuyetNccPhuongAn → 'B')
  - Seq là 3-digit padded (001..012)
  - Type A và B sequence độc lập trong cùng năm
  - Year boundary reset cả A và B

CI gate update (.gitea/workflows/deploy.yml):
- Step "Run integration tests (Infrastructure)" thêm sau Domain tests
- TRX log saved riêng (infra-tests.trx)
- Cả 2 step đều exit non-zero → no deploy

Verify local:
- dotnet test SolutionErp.slnx → Total tests: 71 (54 Domain + 17 Infra) / Passed: 71 / 2.1s
- dotnet build SolutionErp.slnx → 0 error

Phase 3+ pending:
- Application handler tests (CQRS) với EF InMemory hoặc SQLite (~1 ngày)
- API smoke tests qua WebApplicationFactory (~0.5 ngày)
- FE Vitest cho lib utility (~0.5 ngày)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/SolutionErp.Infrastructure.Tests/Common/SqliteDbFixture.cs

@@ -0,0 +1,75 @@
+using Microsoft.Data.Sqlite;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using SolutionErp.Application.Common.Interfaces;
+using SolutionErp.Infrastructure.Persistence;
+
+namespace SolutionErp.Infrastructure.Tests.Common;
+
+// Subclass cho test — override column types SQL Server-specific (`nvarchar(max)`)
+// về TEXT vì SQLite không hỗ trợ. Identity table inherit từ IdentityDbContext
+// dùng kiểu chuẩn nên không cần fix thêm.
+public class TestApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
+    : ApplicationDbContext(options)
+{
+    protected override void OnModelCreating(ModelBuilder modelBuilder)
+    {
+        base.OnModelCreating(modelBuilder);
+
+        // Replace `nvarchar(max)` / `varchar(max)` → `TEXT` cho SQLite compat.
+        foreach (var entity in modelBuilder.Model.GetEntityTypes())
+        {
+            foreach (var prop in entity.GetProperties())
+            {
+                var colType = prop.GetColumnType();
+                if (colType is not null && colType.Contains("max", StringComparison.OrdinalIgnoreCase))
+                {
+                    prop.SetColumnType("TEXT");
+                }
+            }
+        }
+    }
+}
+
+// Fixture build SQLite in-memory ApplicationDbContext mỗi test isolated.
+// Pattern: shared connection (open in fixture) + EnsureCreated() từ model.
+//
+// Tại sao SQLite chứ không InMemory provider?
+//   - InMemory không hỗ trợ transactions — code generator dùng IsolationLevel.Serializable
+//   - SQLite hỗ trợ transactions thật (BEGIN/COMMIT/ROLLBACK), tuy nhiên IsolationLevel
+//     enum value bị provider mapping gracefully (no exception, just default behavior)
+//   - Đủ để test format + sequential increment + scope reset, KHÔNG đủ cho test
+//     race condition thực (cần SQL Server thật)
+public sealed class SqliteDbFixture : IDisposable
+{
+    private readonly SqliteConnection _connection;
+    public TestApplicationDbContext Db { get; }
+
+    public SqliteDbFixture()
+    {
+        // ":memory:" + shared connection — DB tồn tại đến khi connection close.
+        _connection = new SqliteConnection("DataSource=:memory:");
+        _connection.Open();
+
+        var options = new DbContextOptionsBuilder<ApplicationDbContext>()
+            .UseSqlite(_connection)
+            .EnableSensitiveDataLogging()
+            .Options;
+
+        Db = new TestApplicationDbContext(options);
+        Db.Database.EnsureCreated();
+    }
+
+    public void Dispose()
+    {
+        Db.Dispose();
+        _connection.Dispose();
+    }
+}
+
+// Stub IDateTime cho tests deterministic — control thời điểm Year boundary.
+public sealed class FixedDateTime(DateTime utcNow) : IDateTime
+{
+    public DateTime UtcNow { get; set; } = utcNow;
+    public DateTime Now => UtcNow;   // simplification — VPS chạy UTC, không bao giờ dùng local time trong tests
+}