- Health panel relocated below Backtest (last section) per owner — it's
operational detail, not an investment view.
- scheduler._load_source_health now returns only the LATEST entry per source
key (was returning the full refresh history, so siamchart_vintages and
price_snapshot appeared as 2 rows). Verified: 11 sources / 11 unique rows.
- frontend v-for drops slice(0,20) and keys by source key.
Verified in-browser: #health is the last section; 11 unique source rows.