Add AGENTS.md with project documentation

Use Update instead of Include for config/idp-config.json to avoid
conflict with the SDK's default implicit Content item inclusion.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

AGENTS.md

@@ -0,0 +1,74 @@
+# SimpleIdP
+
+Self-hosted OAuth 2.0 / OpenID Connect identity provider built with ASP.NET Core 8.0 and SimpleIdServer.
+
+## Features
+
+- OAuth 2.0 Authorization Code flow with PKCE support
+- OpenID Connect authentication
+- Multiple authentication methods:
+  - Password-based
+  - SMS-based
+  - OTP (One-Time Password)
+  - WebAuthn (FIDO2)
+  - Mobile-based
+  - Email-based
+  - Console-based
+  - Verifiable Presentations
+- Multi-realm support
+- User management with roles and claims
+- Client management with configurable redirect URIs
+- Refresh tokens with configurable expiration
+- Consent management
+
+## Technology Stack
+
+- **Framework**: .NET 8.0
+- **Identity Server**: SimpleIdServer 6.0.*-*
+- **UI**: Razor Pages
+- **Container**: Docker (multi-stage build)
+
+## Configuration
+
+Configuration is loaded from JSON files in the `config/` directory:
+
+- `users.json` - User definitions (username, password, email, roles, claims, consents)
+- `clients.json` - OAuth 2.0 client definitions
+- `realm.json` - Realm configuration
+- `scopes.json` - Available scopes and claim mappers
+- `api.json` - API resource definitions
+
+## Quick Start
+
+### Run Locally
+
+```bash
+dotnet run
+```
+
+The server starts on:
+- HTTPS: `https://localhost:65455`
+- HTTP: `http://localhost:65456`
+
+### Run in Docker
+
+```bash
+docker build -t simpleidp .
+docker run -p 8080:8080 simpleidp
+```
+
+## Default Credentials
+
+The default user is defined in `config/users.json`:
+
+- Username: `administrator`
+- Password: `password`
+- Email: `adm@mail.com`
+
+## Docker Hub
+
+Image: `mareklesko/simpleidp`
+
+## CI/CD
+
+GitLab CI pipeline builds and pushes Docker images on `dev` and `main` branches.

SimpleIdp.csproj

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 		<PackageReference Include="Microsoft.Web.LibraryManager.Build" Version="2.1.175" />
 	</ItemGroup>
 	<ItemGroup>
-	  <Content Include="config\idp-config.json">
+	  <Content Update="config\idp-config.json">
 	    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
 	  </Content>
 	</ItemGroup>