Fix traffic light plot rendering for single-study reviews with many domains

[Copilot]

• Identify root cause 1: facet_grid(space = "free") + degenerate y-axis limits = c(1, 1) → zero-height panels for single-study plots
• Fix scale_y_continuous limits from c(1, 1) to c(0.5, 1.5) in theme_rob_tf (R/helpers.R)
• Identify root cause 2: Generic/ROB1 caption lists every domain by name; with 21+ domains it exceeds the fixed base overhead, squashing the data circles
• Fix get_height (R/helpers.R) to add max(0, ncol(data) - 9) * 0.15 in per extra domain for Generic/ROB1
• Fix nrowspx (app.R) to add max(0, ncol(trafficdf) - 9) * 14 px per extra domain for on-screen display
• Fix nrowsin (app.R) to add same proportional adjustment for download height
• Wire nrowsin() into the downloadtrafficlightplot handler — it was computed but never passed to rob_save(), so the download was still using the old unpadded rec_height
• Final code review and CodeQL scan passed

[mcguinlu]

@copilot I actually think the issue here is that the data uploaded in the issue has >20 domains, which means that the legends is very large and so the actual plot is squished by the autosizing function. Can you take a look and see if I am right, and if so, add some code to handle very large numbers of domains?

[Copilot]

@copilot I actually think the issue here is that the data uploaded in the issue has >20 domains, which means that the legends is very large and so the actual plot is squished by the autosizing functio...

You're right — with 21+ domains the caption (which lists every domain by name, one per line) exceeds the fixed 200px/2.5in overhead entirely, leaving zero vertical space for the actual data circles.

Fixed in commit 5058eff:

• R/helpers.R (get_height): adds max(0, ncol(data) - 9) * 0.15 inches per extra domain column for Generic/ROB1 tools. For 23 columns (21 domains + Study + Overall) this adds 2.1 in, bringing a single-study plot from 2.9 in → 5.0 in.
• robvisapp/app.R (nrowspx): adds the equivalent max(0, ncol(trafficdf) - 9) * 14 px for the on-screen display (240 px → 436 px for the reported case).
• robvisapp/app.R (nrowsin): same proportional adjustment for the download-height reactive.

The baseline of 9 columns and 0.15 in/14 px per extra domain are kept consistent across all three locations and commented with the pixel↔inch relationship.

[mcguinlu]

@copilot - this seems to be working now for the in-app version, but the downloaded version of the image is still squashed (no data circles)

[Copilot]

@copilot - this seems to be working now for the in-app version, but the downloaded version of the image is still squashed (no data circles)

Found it — nrowsin (the reactive that computes the download height with the per-domain adjustment) was being computed correctly but was never actually passed to rob_save(). The download handler was falling back to rob_object$rec_height, which didn't include the domain-count padding.

Fixed in commit 54f7d5b by passing height = nrowsin() explicitly to rob_save() in the download handler.