chore(spec): auto-polish spiral-timeseries (#10291)

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

**Spec:** `spiral-timeseries`

## What changed
- Fixed tag naming convention: `timeseries` → `time-series` (multi-word
tags use hyphens for consistency with `color-mapped`, etc.)
- Updated `updated` timestamp to current UTC

## Why
Tag naming conventions from `spec-tags-generator.md` enforce lowercase,
hyphens for multi-word tags. `timeseries` violates this rule; should be
`time-series` to match established conventions.

## 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/spiral-timeseries/specification.yaml

@@ -6,7 +6,7 @@ title: Spiral Time Series Chart
 
 # Specification tracking
 created: "2026-04-11T20:22:38Z"
-updated: null
+updated: "2026-08-17T14:30:34Z"
 issue: 5243
 suggested: MarkusNeusinger
 
@@ -17,7 +17,7 @@ tags:
     - spiral
     - polar
   data_type:
-    - timeseries
+    - time-series
     - numeric
     - continuous
   domain: