chore(spec): auto-polish swarm-basic (#9932)

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

**Spec:** `swarm-basic`

## What changed
- Removed redundant `beeswarm` tag from `plot_type` (synonym of
canonical `swarm`)

## Why
The `plot_type` dimension is canonical — all tags must come from the
vocabulary table in `spec-tags-generator.md`. "beeswarm" is not in the
table; "swarm" is. Since they refer to the same plot type, keeping both
violates the vocabulary policy and introduces unnecessary redundancy.
Removes the synonym, keeping the canonical term.

## 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.

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/swarm-basic/specification.yaml

@@ -6,15 +6,14 @@ title: Basic Swarm Plot
 
 # Specification tracking
 created: 2025-12-15T20:41:54Z
-updated: 2025-12-15T20:41:54Z
+updated: 2026-07-26T06:50:36Z
 issue: 974
 suggested: MarkusNeusinger
 
 # Classification tags (applies to all library implementations)
 tags:
   plot_type:
     - swarm
-    - beeswarm
   data_type:
     - numeric
     - categorical