monitoring(wealth): re-add milestone annotations (now that PG creds rotated)

Re-applies the milestone annotation commit reverted in 0ef36aec. The
earlier "nothing loads / syntax error" was a red herring: Vault had
rotated the wealthfolio_sync DB password 7 days prior, the K8s Secret
picked it up automatically (pg-sync sidecar still working), but the
Grafana datasource ConfigMap is baked at TF-apply time so Grafana was
sending the old password. Every panel + the new annotation alike
failed with: pq password authentication failed for user wealthfolio_sync.

Fix today: refresh the datasource ConfigMap and roll Grafana.

  scripts/tg apply -target=kubernetes_config_map.grafana_wealth_datasource
  kubectl -n monitoring rollout restart deploy/grafana

Annotation source verified live via /api/ds/query: SQL returns 5
milestone rows correctly. Dashboard charts now show vertical dashed
lines at GBP100k 2021-11-01, GBP250k 2023-07-18, GBP500k 2024-09-19,
GBP750k 2025-08-26, GBP1M 2026-04-18.

KNOWN FOLLOW-UP: Vault rotates pg-wealthfolio-sync every 7 days
(static role). Todays failure will recur unless the Grafana
datasource auto-refreshes. Options:
  1. Annotate Grafana deploy with stakater/reloader so it restarts
     when wealthfolio-sync-db-creds Secret changes.
  2. Switch datasource provisioning to read password from an env var
     sourced from the Secret instead of baking into the ConfigMap.
     Combined with reloader, picks up rotation cleanly.

stacks/monitoring/modules/monitoring/dashboards/wealth.json

@@ -9,6 +9,20 @@
         "iconColor": "rgba(0, 211, 255, 1)",
         "name": "Annotations & Alerts",
         "type": "dashboard"
+      },
+      {
+        "datasource": {"type": "grafana-postgresql-datasource", "uid": "wealth-pg"},
+        "enable": true,
+        "hide": false,
+        "iconColor": "purple",
+        "name": "Milestones",
+        "target": {
+          "rawQuery": true,
+          "editorMode": "code",
+          "format": "table",
+          "refId": "Anno",
+          "rawSql": "WITH daily AS (SELECT d.valuation_date, SUM(d.total_value) AS nw FROM daily_account_valuation d JOIN accounts a ON a.id = d.account_id GROUP BY d.valuation_date), crossings AS (SELECT t, (SELECT MIN(valuation_date) FROM daily WHERE nw >= t::numeric) AS d FROM unnest(ARRAY[100000, 250000, 500000, 750000, 1000000]) AS t) SELECT d::timestamptz AS time, '£' || CASE WHEN t >= 1000000 THEN (t/1000000)::int::text || 'M' ELSE (t/1000)::int::text || 'k' END AS text FROM crossings WHERE d IS NOT NULL ORDER BY d"
+        }
       }
     ]
   },