Enforce doc-first protocol, add SGen, modular plugin docs

- Enforced strict documentation-first AI agent protocol in `.github/copilot-instructions.md` (multi-repo, no auto doc edits, explicit consent, [LOADED_DOCS] prefix, [DOCUMENTATION CHECK] on code changes)
- Updated solution structure: added `docs` folder to solution items for LLM/AI context
- Integrated AyCode SGen (source-generated binary serialization) with forced runtime registration; documented SGen usage and exclusions
- Overhauled plugin `README.md` and added modular docs: `SCHEMA.md`, `DOMAIN_MODEL.md`, `MEASUREMENT.md`, `DATA_LAYER.md`, `AI_SERVICES.md`, `SIGNALR_ENDPOINTS.md`
- Updated `CLAUDE.md` to require reading copilot instructions first
- Switched appsettings connection string to production DB
- Minor doc clarifications, corrects, and project file updates

CLAUDE.md

@@ -1 +1 @@
-Always read `.github/copilot-instructions.md` first — it is the single source of truth for this repo.
+CRITICAL: Your FIRST action in every session MUST be reading `.github/copilot-instructions.md`. Execute ALL session-start instructions found there before responding to any user query. It is the single source of truth for this repo.

Mango.Nop.Core/AcBinaryForcedInit.cs

@@ -0,0 +1 @@
+namespace Mango.Nop.Core { public static class AcBinaryForcedInit { public static void ForceRegister() { System.Console.WriteLine("[SGEN TESTING] AcBinaryForcedInit called."); AyCode.Core.Serializers.Generated.AcBinaryGeneratedWritersInit.Register(); } } }

Mango.Nop.Core/Mango.Nop.Core.csproj

@@ -40,6 +40,12 @@
 		</Reference>
 	</ItemGroup>
 
+	<ItemGroup>
+		<ProjectReference Include="..\..\..\..\..\..\Aycode\Source\AyCode.Core\AyCode.Core.Serializers.SourceGenerator\AyCode.Core.Serializers.SourceGenerator.csproj"
+						  OutputItemType="Analyzer"
+						  ReferenceOutputAssembly="false" />
+	</ItemGroup>
+
 	<ItemGroup>
 		<Folder Include="ExtendedFactories\" />
 		<Folder Include="ExtendedModels\" />

Mango.Nop.Core/NopDependencies/Catalogs/DiscountProductMapping.cs

@@ -5,7 +5,8 @@ namespace Nop.Core.Domain.Discounts;
 /// <summary>
 /// Represents a discount-product mapping class
 /// </summary>
-[AcBinarySerializable(false, true, false, true)]
+// SGen incompatible: DiscountMapping.Id is readonly (new int Id { get; }) — generated reader cannot set it (CS0200)
+//[AcBinarySerializable(false, true, false, true)]
 public partial class DiscountProductMapping : DiscountMapping
 {
     /// <summary>

Mango.Nop.Core/README.md

@@ -89,4 +89,17 @@ Extends AyCode logging infrastructure — for base types see `AyCode.Core/docs/L
 - `linq2db` — data access, `[Association]` / `[Table]` attributes
 - `Microsoft.AspNetCore.Mvc.NewtonsoftJson` — JSON serialization
 - Binary serialization: `AcBinarySerializer` (see `AyCode.Core/docs/BINARY_FORMAT.md`). SignalR transport: `AcSignalR` (see `AyCode.Core/AyCode.Services/docs/SIGNALR.md`).
+- `AyCode.Core.Serializers.SourceGenerator` (ProjectReference, `OutputItemType="Analyzer"`) — compile-time binary serializer. See [`AyCode.Core/docs/BINARY_SOURCE_GEN.md`](../../../../../../Aycode/Source/AyCode.Core/AyCode.Core/docs/BINARY_SOURCE_GEN.md)
 - AyCode DLL references: `AyCode.Interfaces`, `AyCode.Core`, `AyCode.Utils`, `AyCode.Entities` (types only, no runtime nopCommerce dependency)
+
+## AcBinary Source Generator (SGen)
+
+9 types annotated with `[AcBinarySerializable]`. For general SGen docs see [`AyCode.Core/docs/BINARY_SOURCE_GEN.md`](../../../../../../Aycode/Source/AyCode.Core/AyCode.Core/docs/BINARY_SOURCE_GEN.md).
+
+Requires `InternalsVisibleTo("Mango.Nop.Core")` in `AyCode.Core/Properties/AssemblyInfo.cs`.
+
+### Excluded types
+
+| Type | Reason |
+|---|---|
+| `DiscountProductMapping` | Base `DiscountMapping` hides `BaseEntity.Id` with readonly `new int Id { get; }` → CS0200. Uses compiled-expression fallback. |