feat(theme): --settle capture delay for reveal transitions and canvas heroes

Scroll-reveal themes (gotham .reveal, scifi-clean data-sc-reveal) start
content at opacity:0 under JS and fade in ~0.5s after the observer fires;
capturing on WaitVisible(main) catches mid-transition ghosts. --settle adds
a post-wait delay so transitions and canvas animations (cyberpunk rain)
finish before the screenshot.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

cmd/ninja/cmd/theme.go

@@ -27,6 +27,7 @@ func newThemeScreenshotCmd() *cobra.Command {
 	var mobile bool
 	var width, height int
 	var scale float64
+	var settle time.Duration
 	cmd := &cobra.Command{
 		Use:   "screenshot",
 		Short: "Render this theme's showcase page and write preview.png into the repo",
@@ -70,6 +71,7 @@ the rest of the CLI.`,
 				WaitSelector: waitSelector,
 				Timeout:      45 * time.Second,
 				Scale:        scale,
+				Settle:       settle,
 			})
 			if err != nil {
 				return err
@@ -89,6 +91,7 @@ the rest of the CLI.`,
 					WaitSelector: waitSelector,
 					Timeout:      45 * time.Second,
 					Scale:        scale,
+					Settle:       settle,
 				})
 				if err != nil {
 					return err
@@ -128,6 +131,7 @@ the rest of the CLI.`,
 							Timeout:      45 * time.Second,
 							Mode:         mode,
 							Scale:        scale,
+							Settle:       settle,
 						})
 						if err != nil {
 							return err
@@ -159,6 +163,7 @@ the rest of the CLI.`,
 	cmd.Flags().IntVar(&height, "height", 900, "Desktop viewport height")
 	cmd.Flags().StringVar(&pages, "pages", "", "Comma-separated page slugs to capture into --screenshots-dir (e.g. /,/blog,/about)")
 	cmd.Flags().StringVar(&screenshotsDir, "screenshots-dir", "screenshots", "Directory for --pages captures (packed into the .bnp)")
+	cmd.Flags().DurationVar(&settle, "settle", 0, "Extra wait after --wait matches before capturing (e.g. 1500ms; lets reveal transitions and canvas animations finish)")
 	cmd.Flags().Float64Var(&scale, "scale", 1, "Device scale factor (2 = retina PNGs at Width*2 x Height*2)")
 	cmd.Flags().StringVar(&modes, "modes", "", `Comma-separated color modes for --pages captures: "light", "dark" or "light,dark" (sets the bn-theme cookie per capture; empty = site default, unsuffixed filenames)`)
 	return cmd

internal/shot/shot.go

@@ -26,6 +26,7 @@ type Options struct {
 	Timeout      time.Duration // overall navigation+capture timeout
 	Mode         string        // "" (site default), "light" or "dark" — sets the bn-theme cookie + emulated prefers-color-scheme before navigation
 	Scale        float64       // device scale factor; 0 = 1.0. 2 captures retina PNGs (Width*2 × Height*2 px)
+	Settle       time.Duration // extra wait after WaitSelector before capturing — lets scroll-reveal transitions and canvas animations finish (0 = capture immediately)
 }
 
 // PreviewURL composes the gallery-page URL with the render-only override.
@@ -99,6 +100,9 @@ func Capture(ctx context.Context, opts Options) ([]byte, error) {
 	} else {
 		tasks = append(tasks, chromedp.WaitReady("body", chromedp.ByQuery))
 	}
+	if opts.Settle > 0 {
+		tasks = append(tasks, chromedp.Sleep(opts.Settle))
+	}
 	if opts.FullPage {
 		tasks = append(tasks, chromedp.FullScreenshot(&buf, 90))
 	} else {