stats: core-7 economy page with CPI index levels, rebase and categories

- /stats/economy defaults multi-country charts to CAN KOR CHN JPN USA NLD CUW,
  with add-a-country chips and an EU 27 comparison line
- CPI index levels rebased to a chosen base year, index/YoY toggle,
  categories (food, energy, housing, core) where the source has them
- new no-key collectors: oecd (CPI categories, 10y yields), statcan (CPI);
  bis WS_LONG_CPI, FRED US CPI categories, Eurostat prc_hicp_minr, WB FP.CPI.TOTL
- Canada added as a region; CBS Curacao fallbacks for growth/unemployment
- timers stats-oecd and stats-statcan

deploy/stats-collector/stats-oecd.timer

@@ -0,0 +1,11 @@
+[Unit]
+Description=/stats collector: OECD SDMX CPI categories and 10-year yields, Thursdays
+
+[Timer]
+OnCalendar=Thu *-*-* 06:35:00 Europe/Amsterdam
+RandomizedDelaySec=10min
+Persistent=true
+Unit=stats-collector@oecd.service
+
+[Install]
+WantedBy=timers.target