Refactor plotting logic into separate package and update .gitignore

- Move PlotIR function from pkg/convolve to pkg/plot package
- Update main.go to use new plot package
- Clean up convolve package imports
- Add comprehensive .gitignore entries for test files and generated outputs
- Allow only recorded.wav and sweep.wav in testfiles directory
- Ignore all generated audio files and plot images

main.go

@@ -6,6 +6,7 @@ import (
 	"os"
 
 	"valhallir-deconvolver/pkg/convolve"
+	"valhallir-deconvolver/pkg/plot"
 	"valhallir-deconvolver/pkg/wav"
 
 	"github.com/urfave/cli/v2"
@@ -78,6 +79,10 @@ func main() {
 				Usage: "Cut filter slope in dB/octave (12, 24, 36, 48, ...; default 12)",
 				Value: 12,
 			},
+			&cli.BoolFlag{
+				Name:  "plot-ir",
+				Usage: "Plot the generated regular IR waveform to ir_plot.png",
+			},
 		},
 		Action: func(c *cli.Context) error {
 			// Read sweep WAV file
@@ -185,6 +190,16 @@ func main() {
 				return err
 			}
 
+			// Plot IR waveform if requested
+			if c.Bool("plot-ir") {
+				log.Printf("Plotting IR waveform to ir_plot.png...")
+				err := plot.PlotIR(ir, sampleRate, c.String("output"))
+				if err != nil {
+					return fmt.Errorf("failed to plot IR: %v", err)
+				}
+				log.Printf("IR plot saved as ir_plot.png")
+			}
+
 			// Generate MPT IR if requested
 			if c.Bool("mpt") {
 				log.Println("Generating minimum phase transform...")