feat: implement authentication system for API Gateway and FileService

- Add JWT Bearer token validation to API Gateway with restricted CORS
- Add cookie-based JWT validation to FileService for browser image requests
- Create shared authentication infrastructure in FictionArchive.Service.Shared
- Update frontend to set fa_session cookie after OIDC login
- Add [Authorize] attributes to GraphQL mutations with role-based restrictions
- Configure OIDC settings for both services in docker-compose

Implements FA-17: Authentication for microservices architecture

FictionArchive.Service.FileService/Controllers/S3ProxyController.cs

@@ -2,6 +2,7 @@ using System.Web;
 using Amazon.S3;
 using Amazon.S3.Model;
 using FictionArchive.Service.FileService.Models;
+using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Options;
@@ -10,6 +11,7 @@ namespace FictionArchive.Service.FileService.Controllers
 {
     [Route("api/{*path}")]
     [ApiController]
+    [Authorize]
     public class S3ProxyController : ControllerBase
     {
         private readonly AmazonS3Client _amazonS3Client;

FictionArchive.Service.FileService/FictionArchive.Service.FileService.csproj

@@ -21,6 +21,7 @@
       <PackageReference Include="AWSSDK.S3" Version="4.0.13.1" />
       <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="9.0.0" />
       <PackageReference Include="Swashbuckle.AspNetCore" Version="10.0.1" />
+      <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="8.0.11" />
     </ItemGroup>
 
     <ItemGroup>

FictionArchive.Service.FileService/Program.cs

@@ -34,6 +34,10 @@ public class Program
         
         #endregion
         
+        // Add authentication with cookie support
+        builder.Services.AddOidcCookieAuthentication(builder.Configuration);
+        builder.Services.AddFictionArchiveAuthorization();
+        
         builder.Services.Configure<ProxyConfiguration>(builder.Configuration.GetSection("ProxyConfiguration"));
         
         // Add S3 Client
@@ -60,6 +64,9 @@ public class Program
             app.UseSwaggerUI();
         }
 
+        app.UseAuthentication();
+        app.UseAuthorization();
+        
         app.MapHealthChecks("/healthz");
         
         app.MapControllers();

FictionArchive.Service.FileService/appsettings.json

@@ -18,5 +18,14 @@
     "AccessKey": "REPLACE_ME",
     "SecretKey": "REPLACE_ME"
   },
+  "OIDC": {
+    "Authority": "https://auth.orfl.xyz/application/o/fictionarchive/",
+    "ClientId": "fictionarchive-files",
+    "Audience": "fictionarchive-api",
+    "ValidateIssuer": true,
+    "ValidateAudience": true,
+    "ValidateLifetime": true,
+    "ValidateIssuerSigningKey": true
+  },
   "AllowedHosts": "*"
 }