Refactor runner and installation scripts for improved functionality

- Removed the `--disable-hiprt` flag from the runner command, simplifying the rendering options for users.
- Updated the `jiggablend-runner` script and README to reflect the removal of the HIPRT control flag, enhancing clarity in usage instructions.
- Enhanced the installation script to provide clearer examples for running the jiggablend manager and runner, improving user experience during setup.
- Implemented a more robust GPU backend detection mechanism, allowing for better compatibility with various hardware configurations.

internal/runner/tasks/encode.go

@@ -298,6 +298,9 @@ func (p *EncodeProcessor) Process(ctx *Context) error {
 				ctx.Info(line)
 			}
 		}
+		if err := scanner.Err(); err != nil {
+			log.Printf("Error reading encode stdout: %v", err)
+		}
 	}()
 
 	// Stream stderr
@@ -311,6 +314,9 @@ func (p *EncodeProcessor) Process(ctx *Context) error {
 				ctx.Warn(line)
 			}
 		}
+		if err := scanner.Err(); err != nil {
+			log.Printf("Error reading encode stderr: %v", err)
+		}
 	}()
 
 	err = cmd.Wait()