feat(application): PSD layer separation and image quality/count threading

Convert GPT Image 2 layered PSD output into canvas image/text nodes with a
local separation fallback (new layer_separation.go, oov/psd dependency),
default layer-separation/edit-elements output_format to psd, and thread
imageQuality/imageCount through project generation and job processing.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/internal/application/generator_task.go

@@ -268,6 +268,7 @@ func normalizeMoveObjectInput(input design.GeneratorTaskInputArgs) design.Genera
 		input.DstBox = &box
 	}
 	input.ImageURL = strings.TrimSpace(input.ImageURL)
+	input.OutputFormat = strings.TrimSpace(input.OutputFormat)
 	input.Prompt = strings.TrimSpace(input.Prompt)
 	input.Resolution = strings.TrimSpace(input.Resolution)
 	input.AspectRatio = strings.TrimSpace(input.AspectRatio)
@@ -279,6 +280,10 @@ func normalizeLayerSeparationInput(input design.GeneratorTaskInputArgs) design.G
 		input.ImageURL = strings.TrimSpace(input.Image[0])
 	}
 	input.ImageURL = strings.TrimSpace(input.ImageURL)
+	input.OutputFormat = strings.TrimSpace(input.OutputFormat)
+	if input.OutputFormat == "" {
+		input.OutputFormat = "psd"
+	}
 	input.Prompt = strings.TrimSpace(input.Prompt)
 	input.Resolution = strings.TrimSpace(input.Resolution)
 	input.AspectRatio = strings.TrimSpace(input.AspectRatio)
@@ -777,15 +782,19 @@ func generatorTaskInputArgsForNodeAction(target design.Node, req design.NodeActi
 	}
 	width, height := design.GeneratedImageDimensions(imageSize)
 	input := design.GeneratorTaskInputArgs{
-		AspectRatio: aspectRatioLabel(int64(math.Round(width)), int64(math.Round(height))),
-		Image:       []string{target.Content},
-		ImageURL:    target.Content,
-		Prompt:      generatorTaskPromptForNodeAction(req),
-		Resolution:  resolutionLabel(imageSize),
+		AspectRatio:  aspectRatioLabel(int64(math.Round(width)), int64(math.Round(height))),
+		Image:        []string{target.Content},
+		ImageURL:     target.Content,
+		OutputFormat: strings.TrimSpace(req.Options["output_format"]),
+		Prompt:       generatorTaskPromptForNodeAction(req),
+		Resolution:   resolutionLabel(imageSize),
 	}
 	if normalizeNodeAction(req.Action) == "move-object" {
 		input.SrcBox, input.DstBox = moveObjectBoxesFromSelection(req.Selection)
 	}
+	if normalizeNodeAction(req.Action) == "edit-elements" && input.OutputFormat == "" {
+		input.OutputFormat = "psd"
+	}
 	return input
 }