[CLAUDE] Docs: chốt session 4 — Budget BE module + 14 Solutions users

- STATUS.md: header Phase 7 + 3 row Recently Done (Budget BE / 14 users / Docs cleanup) + cumulative cột mới (51 tables / 14 mig / ~124 endpoints)
- HANDOFF.md: TL;DR session 4 (2 milestone Budget BE + 14 users) + Cảnh báo session 5 + Priority 0 (FE Budget + PE/HD integration + PE feature gap) + Credentials 30 user
- migration-todos.md: Phase 7 thêm section D Budget done + Phase 8 mới (FE Budget pages + integration) + pending migrations Budget
- architecture.md: §10 Budget module mới (ERD + state machine + auto-recompute + integration roadmap)
- database/schema-diagram.md: migration history rows 13+14 + §12 Budget ERD chi tiết
- ef-core-migration SKILL: migration 14 entry + Phase 8 pending Budget refinement
- CLAUDE.md root + docs: modules table thêm Budget row + scope Budget + count 51 bảng / 14 mig
- Session log 2026-04-28-chot-session-4-budget.md (10+ section detailed)

Stats: 51 tables (+4 Budget), 14 migrations (+AddBudgets), ~124 endpoints (+11 Budget),
30 demo user (16 sample + 14 Solutions thật), 38 gotchas, ~340 LOC Budget CQRS.
FE Budget pages chưa làm — Priority 0 session 5.

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

.claude/skills/ef-core-migration/SKILL.md

@@ -1,6 +1,6 @@
 ---
 name: ef-core-migration
-description: Tạo/sửa/revert EF Core 10 migration cho SOLUTION_ERP. Dùng khi thêm entity mới, thay đổi schema, rollback migration, debug DesignTimeDbContextFactory fail. Đã có 13 migration sẵn (Init → AddPurchaseEvaluationCodeSequences). Snapshot + Designer + Migration 3-file rule bắt buộc commit đủ.
+description: Tạo/sửa/revert EF Core 10 migration cho SOLUTION_ERP. Dùng khi thêm entity mới, thay đổi schema, rollback migration, debug DesignTimeDbContextFactory fail. Đã có 14 migration sẵn (Init → AddBudgets). Snapshot + Designer + Migration 3-file rule bắt buộc commit đủ.
 when-to-use:
   - "thêm migration"
   - "EF Core migration"
@@ -16,7 +16,7 @@ when-to-use:
 
 > **Context:** .NET 10 + EF Core 10 + SQL Server. DbContext: `ApplicationDbContext` ở `Infrastructure/Persistence/`. Startup: `SolutionErp.Api`.
 
-## Migration history (12 migration hiện có)
+## Migration history (14 migration hiện có)
 
 | # | Name | Tables added / changed |
 |---|---|---|
@@ -33,13 +33,22 @@ when-to-use:
 | 11 | `AddRoleShortNameAndUserDepartment` | +Role.ShortName + User.DepartmentId/Position (cột thêm, không bảng mới) |
 | **12** | **`AddPurchaseEvaluations`** | **10 bảng module Duyệt NCC: PurchaseEvaluations + Suppliers + Details + Quotes + Approvals + Changelogs + Attachments + WorkflowDefinitions/Steps/StepApprovers** |
 | **13** | **`AddPurchaseEvaluationCodeSequences`** | **1 bảng `PurchaseEvaluationCodeSequences` (Prefix PK, LastSeq) — atomic sequence cho MaPhieu format `PE/{YYYY}/{A\|B}/{Seq:D3}`** |
+| **14** | **`AddBudgets`** | **4 bảng module Ngân sách: Budgets + BudgetDetails + BudgetApprovals + BudgetChangelogs. + nullable FK index `Contracts.BudgetId` & `PurchaseEvaluations.BudgetId`** |
 
-Total: **47 bảng** dbo + `__EFMigrationsHistory`. Xem `docs/database/schema-diagram.md` ERD đầy đủ.
+Total: **51 bảng** dbo + `__EFMigrationsHistory`. Xem `docs/database/schema-diagram.md` ERD đầy đủ.
 
-**Phase 7 pending (session sau):**
+**Phase 7 pending:**
 - `AddPePaymentTermFields` — tách `PurchaseEvaluations.PaymentTerms` JSON thành 6 column riêng
 - `AddPeDepartmentOpinions` — thêm 4 field Ý kiến phòng ban (Phê duyệt/CCM/MuaHàng/SM-PM) vào header hoặc table riêng
 
+**Phase 8 pending (Budget refinement):**
+- `AddBudgetCodeSequences` — atomic sequence khi format MaNganSach chốt (mirror Contract/PE pattern, hiện Random.Shared)
+- `AddBudgetVersionedWorkflow` — nếu Solutions cần admin config UI (3 bảng `BudgetWorkflowDefinitions/Steps/StepApprovers` + `Budgets.WorkflowDefinitionId?`)
+
+**Phase 7 update (2026-04-28):**
+- Migration 14 `AddBudgets` — 4 bảng (Budgets/Details/Approvals/Changelogs) + 2 cột `BudgetId?` thêm vào Contracts & PurchaseEvaluations. Workflow hardcoded `BudgetPolicy.Default` (chưa versioned).
+- 14 demo user thật `@solutions.com.vn` qua `SeedDemoUsersAsync` reconcile (PRO 5 + CCM 7 + ISO 1 + CEO 1).
+
 **Phase 6 update (2026-04-24):**
 - Enum `PurchaseEvaluationAttachmentPurpose.ComparisonTable = 4` mới (file bảng so sánh tổng).
   Int column, không cần migration.