feat: implement real-time reading progress and refactor profile to CQRS

.agent/skills/nexus-architecture-standards/SKILL.md

@@ -36,6 +36,13 @@ This skill defines the architectural guardrails for the NexusReader project to e
 +- Event handlers MUST use `Func<Task>` or async-compatible patterns.
 +- UI components MUST await all service calls and use `InvokeAsync(StateHasChanged)` for state updates within async contexts.
 
+### 6. Database Schema Changes
+- Every change to a Domain entity or DbContext MUST be followed by the generation of a new EF Core migration.
+- **Mandatory Commands**:
+  - `dotnet ef migrations add <MigrationName> --project src/NexusReader.Data --startup-project src/NexusReader.Web.New`
+  - `dotnet ef database update --project src/NexusReader.Data --startup-project src/NexusReader.Web.New`
+- Ensure the migration is applied to all local development environments before proceeding with feature verification.
+
 ## Audit Scripts
 - [ArchCheck.sh](scripts/arch_check.sh): A shell script to scan for illegal cross-layer imports.