web: fix topology device markers placed in the water

[armcconnell]

Resolves: #652

Summary of Changes

• Fix device markers on the topology map and globe that were rendered in the ocean. They were positioned as a metro centroid plus a fixed 0.3° (~25 mi) radial fanout, ignoring real device locations; for coastal metros like NYC that arc placed markers offshore in the Atlantic and the harbor.
• Default to a much tighter metro-centroid fanout (radius 0.3° → 0.04°, ~3 mi) so co-located devices stay visually separated without landing in the water.
• Add a "Precise locations" toggle (available on both map and globe) that anchors each device at its real facility coordinates, with a small jitter (~0.5 mi) so devices sharing a facility remain individually clickable. Devices with no facility coordinates fall back to the fanout.
• Extract the duplicated calculateDevicePosition from the map and globe into one shared, unit-tested helper (computeDevicePositions).
• Expose per-device facility latitude/longitude from the topology API (LEFT JOIN dz_facilities_current via location_pk).

The graph view is non-geo (force-directed), so it is unaffected.

Diff Breakdown

Category	Files	Notes
Core logic	5	shared helper (new), map, globe, topology API handler, context toggle
Scaffolding	2	control-bar toggle, api.ts type
Tests	1	devicePositions.test.ts (new)

Most of the change is the shared positioning helper plus wiring; the rest is the toggle and the API field.

Key files (click to expand)

• web/src/components/topology/devicePositions.ts — new pure helper: fanout (default, tight radius) + facility-anchored (with co-located jitter) + fallback
• web/src/components/topology-map.tsx / topology-globe.tsx — use the shared helper, keyed off the toggle; removed the duplicated local functions
• web/src/components/topology/TopologyContext.tsx — new preciseLocations overlay toggle (URL-synced like other overlays)
• web/src/components/topology/TopologyControlBar.tsx — "Precise locations" control on map and globe
• api/handlers/topology.go — facility lat/lng on the topology Device

Testing Verification

• New unit tests for the positioning helper: lone device sits on the metro center; co-metro devices stay within the (small) fanout radius and remain distinct; facility mode anchors a lone device exactly on its facility coords; co-located devices jitter within the facility radius and stay distinct; a device with no facility coords falls back to the metro fanout rather than [0,0].
• Full web unit suite passes (185 tests).
• Verified against production data that all 97 activated devices have facility coordinates (so facility mode resolves real locations rather than falling back), and that up to 4 devices share a facility (hence the co-located jitter).