Draft spec for the four-dashboard rebuild called out in KEEP-573 Phase 1 E.
Splits the current single "KeeperHub" dashboard by audience:

- A. Managed Client SLO (exec + Sky/Ajna account team)
- B. Platform Health (TechOps/DevOps on-call)
- C. Customer Workflows (per-org support debugging)
- D. Growth + Revenue (founders + revenue side)

Each dashboard section: variables, panel list with PromQL/LogQL,
linked alerts, owner suggestion, open questions. Implementation plan
targets the new grafana git-sync path adopted on 2026-05-20, with
files landing under grafana/keeperhub-dashboards/git-sync/.

Open questions for the review at the bottom of the doc.

Closes the Phase 1 E acceptance item on the parent ticket. Owners
finalized in this PR's review.

Bulk error_type reclassification (backfill re-run, classifier rule
change, manual SQL fix) makes the DB-sourced gauge's error_type
label-value series move at one scrape. PromQL's increase() reads the
gain as new errors while the loss is treated as a counter reset,
producing a phantom positive bump that contaminates SLI panels for
one window-length.

Documents the symptom + how to recognise it so future engineers don't
chase a phantom incident, and references the KEEP-592 analysis.