feat(admin): add pipeline diagnostic script + extraction card UX improvements

- Add scripts/check_pipeline.py: read-only diagnostic for pricing pipeline
  row counts, date range analysis, HAVING filter impact, join coverage
- Add description field to all 12 workflows in workflows.toml
- Parse and display descriptions on extraction status cards
- Show spinner + "Running" state with blue-tinted card border
- Display start time with "running..." text for active extractions

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -7,6 +7,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 ## [Unreleased]
 
 ### Added
+- **Pipeline diagnostic script** (`scripts/check_pipeline.py`) — read-only script that reports row counts at every layer of the pricing pipeline (staging → foundation → serving), date range analysis, HAVING filter impact, and join coverage. Run on prod to diagnose empty serving tables.
+- **Extraction card descriptions** — each workflow card on the admin pipeline page now shows a one-line description explaining what the data source is (e.g. "EU geographic boundaries (NUTS2 polygons) from Eurostat GISCO"). Descriptions defined in `workflows.toml`.
+- **Running state indicator** — extraction cards show a spinner + "Running" label with a blue-tinted border when an extraction is actively running, replacing the plain Run button. Cards also display the start time with "running..." text.
+
 - **Interactive Leaflet maps** — geographic visualization across 4 key placements using self-hosted Leaflet 1.9.4 (GDPR-safe, no CDN):
   - **Markets hub** (`/markets`): country bubble map with circles sized by total venues, colored by avg market score (green ≥ 60, amber 30-60, red < 30). Click navigates to country overview.
   - **Country overview articles**: city bubble map loads after article render, auto-fits bounds, click navigates to city page. Bubbles colored by market score.