[ADD] Added endpoint for providing files

Manager.App/Controllers/FileController.cs

@@ -0,0 +1,22 @@
+using Manager.App.Services;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Manager.App.Controllers;
+
+[ApiController]
+[Route("api/v1/[controller]")]
+public class FileController(ILibraryService libraryService) : ControllerBase
+{
+    [HttpGet("provide")]
+    public async Task<IActionResult> ProvideFile([FromQuery(Name = "id")] Guid id, CancellationToken cancellationToken)
+    {
+        var fileResult = await libraryService.GetFileByIdAsync(id, cancellationToken);
+        if (!fileResult.IsSuccess)
+        {
+            return BadRequest(fileResult.Error);
+        }
+
+        var libFile = fileResult.Value;
+        return File(libFile.DataStream, libFile.MimeType, libFile.FileName);
+    }
+}