feat(config): make Equipment.DriverInstanceId nullable + driver-less AdminUI support + migration

docs/plans/2026-06-08-driverless-equipment-namespace-design.md

@@ -106,6 +106,15 @@ In `cmd_populate_equipment`:
   become no-ops; remove for clarity. Keep the `Namespace` INSERT/teardown.
 - Fix the stale `# … "an Equipment namespace has a driver" expectations` comment.
 
+### AdminUI — two production derefs (found at build time, not by the grep sweep)
+Making the column nullable surfaced two `.razor` sites the impact grep missed (caught by `TreatWarningsAsErrors`):
+- `Components/Pages/Clusters/TagEdit.razor:191` — `db.Equipment.Where(e => driverIds.Contains(e.DriverInstanceId))` (CS8604).
+  Behavior-preserving fix: guard `e.DriverInstanceId != null && …` (SQL already excludes NULL from an `IN` set, so this only satisfies the compiler).
+- `Components/Pages/Clusters/EquipmentEdit.razor` — the equipment editor loads `DriverInstanceId` into a non-null
+  `FormModel` (line 183, CS8601) and **mandates** a driver on save (`"Pick a driver instance."`). Decision: give it
+  **full driver-less support** — `FormModel.DriverInstanceId` → `string?`, add a "(none / driver-less)" option to the
+  driver dropdown, relax the mandatory-driver validation, and persist NULL when none is selected (normalize empty → null).
+
 ### Noted, not changing (YAGNI)
 - `sp_ComputeGenerationDiff` includes `DriverInstanceId` in a `CHECKSUM(...)`. It is NULL-tolerant for
   this one-time transition and sits on the **dormant** generation-diff path (the active deploy gate is