BanyanDB self-observability layer (SWIP-15)

Adds a new BanyanDB layer under Self-Observability — Cluster / Container / Group dashboards plus a role-aware Deployment topology — and the widget + deployment-config infrastructure it needed. Pairs with OAP backend SWIP-15 (meter_banyandb_* cluster / meter_banyandb_instance_* container / meter_banyandb_endpoint_* group).

Dashboards

• Cluster / Container / Group views. Container panels adapt to the container's role (liaison / data / lifecycle); Group panels split per data model (measure / stream / trace / property). Panels self-gate on the role attribute and on data presence.
• Disk Used / Total per data path in one widget. Removed the redundant UI-side *100 on disk / system-memory percent (the MAL already scales), and the spurious *1000 on histogram-p99 latencies (the MAL's histogram() already emits ms).

Widget capabilities (generic)

• Card format: "enum" — a translatable value→label map (e.g. 1 → OK, 0 → Failed), editable in the dashboards admin and the translations editor.
• duration time-ago format; line-chart axes + tooltips use scientific notation for large magnitudes.
• Instance-list badge configurable per layer (instances.badge).

Deployment topology

• Role-to-role edge metrics: up to 3 client-side primaries shown inline with short aliases (e.g. W / R), flowing onto one line or stacking by edge length; the selected-edge panel keeps the full client | server breakdown; the Flows sub-tab tables every edge per role-pair.
• Per-role health-ring legend showing each role's own ring metric and its threshold bands (config-driven, no hard-coded metric).
• The deployment role model (clustering, per-role node metrics, role-pair edge metrics) is editable in the Layer-dashboards admin.

Validation

• Templates (metrics, MQE, entity scopes, units) validated against a live OAP.
• tsc × 3, ESLint, i18n catalog validation, license-eye, and unit tests (BFF 189 / UI 85) all pass.