chore(spec): auto-polish cat-box-strip (#6522)

Automated spec polish from `daily-regen` pre-flight.

**Spec:** `cat-box-strip`

## What changed
- Removed `combined` from `plot_type` (not in canonical vocabulary;
belongs in features or as individual types)
- Reformatted Data section to match template structure with field
definitions and size guidance

## Why
- `combined` is listed in the canonical features vocabulary (Layout
category), not plot_type. The plot_type dimension is canonical;
out-of-vocab tags must be removed.
- Data section now includes formal column definitions with types and
recommended data size, matching the canonical template structure.

## Hard guarantees from the prompt
- `id`, `issue`, `created` unchanged
- No semantic changes (data shape, plot type, requirements identical)
- `updated` bumped to current UTC

Auto-merge enabled — will merge once required checks pass. The skip-gate
in `daily-regen` prevents stacking polish PRs for this spec.

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Claude <noreply@anthropic.com>

Author: 3 people

plots/cat-box-strip/specification.md

@@ -13,19 +13,17 @@ A combined visualization that overlays individual data points (strip plot) on to
 
 ## Data
 
-The visualization requires:
-- **Categorical variable**: Groups/categories
-- **Numeric variable**: Values to analyze
-
-Example structure:
+- `category` (categorical) - Groups or categories to compare
+- `value` (numeric) - Numeric values to analyze
+- Size: 50-500+ points (larger samples better reveal distribution shape)
+- Example:
 ```
 Category | Value
 ---------|-------
 A        | 45.2
 A        | 52.1
 B        | 38.7
 B        | 41.3
-...
 ```
 
 ## Notes

plots/cat-box-strip/specification.yaml

@@ -1,11 +1,11 @@
 spec_id: cat-box-strip
 title: Box Plot with Strip Overlay
 created: '2025-12-30T12:00:00Z'
-updated: '2025-12-30T12:00:00Z'
+updated: '2026-05-13T05:24:55Z'
 issue: 2695
 suggested: claude-code
 tags:
-  plot_type: [box, strip, combined]
+  plot_type: [box, strip]
   domain: [statistics]
   features: [overlay, distribution, quartiles]
   data_type: [categorical, numeric]