refactor(drivers): delete the dead discovered-node injection path (§8.2, #507)

#507 was filed as "injection inert in v3, re-migrate onto the raw subtree".
Reading it, the retained code is not revivable: it resolves equipment from
EquipmentNode.DriverInstanceId UNION EquipmentTags, and BOTH are structurally
empty in v3 (AddressSpaceComposer always constructs EquipmentNode with a null
DriverInstanceId; DeploymentArtifact hard-codes an empty EquipmentTags set).
Removing the guard would have changed a log line and injected nothing. So it
is deleted rather than fixed, and #507 closes as superseded by /raw
browse-commit.

Removed: HandleDiscoveredNodes, PartitionDiscoveredByDeviceHost,
ShouldWarnPartition, PlansRoutingEqual, ApplyDiscoveredPlansForDriver,
_discoveredByDriver, the redeploy re-inject tail, DiscoveredNodeMapper,
DiscoveredInjection, AddressSpaceApplier.MaterialiseDiscoveredNodes,
OpcUaPublishActor.MaterialiseDiscoveredNodes, and the Runtime-local copies of
CapturingAddressSpaceBuilder/DiscoveredNode.

The connect-time discovery loop goes too (StartDiscovery, RediscoverTick,
HandleRediscoverAsync, DiscoveredNodesReady, TriggerRediscovery). With
injection gone it had no consumer, and leaving it would either dead-letter or
keep browsing real devices up to ~15x per connect to drop the result.
ITagDiscovery itself stays — the /raw browse picker drives it through
Commons/Browsing/DiscoveryDriverBrowser, which never went through the actor,
so the picker is unaffected.

deferment.md §4.4 called the 18 DiscoveryInjectionDormantV3 tests "Real —
blocked on #507". They are not: they assert an equipment-rooted graft
(EquipmentRootNodeId == "EQ-1") that v3 cannot produce, so they could never
have unskipped as written. Deleted along with DiscoveredNodeMapperTests, the
CapturingAddressSpaceBuilder tests, and the MaterialiseDiscoveredNodes tests
in AddressSpaceApplierTests/OpcUaPublishActorTests. Runtime.Tests skipped:
31 -> 13.

IHostConnectivityProbe is deliberately NOT resolved here. GetHostStatuses()
has no production call site and nothing writes a DriverHostStatus row, but the
table was re-created in the v3 initial migration, so deleting on inference
would be wrong. Split to Gitea #521 with both options costed.

CLAUDE.md, docs/drivers/{Galaxy,TwinCAT,MTConnect}.md updated — they described
the seam as dead.

Build clean; Runtime.Tests 476 passed / 13 skipped; OpcUaServer.Tests 362
passed / 4 skipped.

CLAUDE.md

@@ -155,17 +155,48 @@ Galaxy `mx_data_type` values map to OPC UA types (Boolean, Int32, Float, Double,
 
 `DeployWatcher` (`src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/Browse/DeployWatcher.cs`) polls the gateway's deploy-event signal and raises `IRediscoverable.OnRediscoveryNeeded` when the Galaxy redeploys.
 
-⚠️ **Nothing consumes that signal.** No type under `src/Server/` or `src/Core/` subscribes to
-`OnRediscoveryNeeded` — the only `+=` handlers in `src/` are Galaxy re-raising its own watcher's event
-onto its own interface (`GalaxyDriver.cs:586`). `DriverHostActor.HandleDiscoveredNodes`
-(`src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverHostActor.cs:986-1002`) short-circuits with an
-unconditional `return;` — discovered-node injection is **dormant in v3** because raw tags are authored
-through the `/raw` browse-commit flow instead. A Galaxy redeploy therefore does **not** change the
-served address space; a config redeploy is required. The same inert-signal gap affects TwinCAT,
-MQTT/Sparkplug and MTConnect, and `IHostConnectivityProbe` is likewise unconsumed (`GetHostStatuses()`
-has no production call site; nothing ever writes a `DriverHostStatus` row). Tracked as Gitea **#518**
-(no consumer) and **#507** (re-migrate injection onto the raw subtree) — note that fixing either alone
-changes nothing observable.
+**The signal is consumed as an operator prompt, not as an address-space rebuild** (§8.2, 2026-07-27).
+`DriverInstanceActor` subscribes in `PreStart` and unsubscribes in `PostStop` — the detach is
+load-bearing, because the `IDriver` instance outlives the actor when the host respawns a child around
+the same driver object. A raise is recorded and rides the driver-health snapshot
+(`DriverHealthChanged.RediscoveryNeededUtc` / `.RediscoveryReason`) to the AdminUI `/hosts` page as a
+**"re-browse" chip**.
+
+⚠️ **It is advisory: a Galaxy redeploy still does NOT change the served address space.** v3 authors raw
+tags explicitly through the `/raw` browse-commit flow, so an operator must re-browse the device and
+commit. Injecting nodes at runtime would materialise nodes nobody approved and no deployment artifact
+records.
+
+Two gotchas if you touch this:
+
+- `PublishHealthSnapshot` dedups on a health fingerprint. The rediscovery timestamp **must** stay in
+  that tuple, or a raise on an otherwise-unchanged Healthy driver is swallowed and never reaches the
+  operator. Pinned by `DriverInstanceActorRediscoverySignalTests`.
+- The shared test `StubDriver.GetHealth()` returns `DateTime.UtcNow`, so its fingerprint differs on
+  every call and the dedup never engages — a test built on it passes vacuously. The rediscovery tests
+  use a stub with stable health for exactly this reason.
+
+**#507 is closed as superseded, and the injection path is deleted.** Its retained code read
+`EquipmentNode.DriverInstanceId` and `EquipmentTags`, both *structurally empty* in v3
+(`AddressSpaceComposer.cs`, `DeploymentArtifact.cs`), so removing the guard would have changed a log
+line and injected nothing. Gone with it: `HandleDiscoveredNodes`, `PartitionDiscoveredByDeviceHost`,
+`ApplyDiscoveredPlansForDriver`, the redeploy re-inject tail, `DiscoveredNodeMapper`,
+`AddressSpaceApplier.MaterialiseDiscoveredNodes`, the connect-time discovery loop
+(`StartDiscovery`/`RediscoverTick`/`DiscoveredNodesReady`/`TriggerRediscovery`), and the 18
+`DiscoveryInjectionDormantV3` tests — v2 characterization tests asserting an equipment-rooted graft
+(`EquipmentRootNodeId == "EQ-1"`) that v3 cannot produce. `ITagDiscovery` itself stays: the `/raw`
+browse picker drives it through `Commons/Browsing/DiscoveryDriverBrowser`, which never went through
+the actor.
+
+**Deliberately NOT built: a discovered-vs-authored drift detector.** Modbus, S7, MQTT, AbLegacy and Sql
+all *echo authored config* from `DiscoverAsync` rather than browsing the device, so such a diff is
+permanently empty for them — another plausible-looking inert seam. `IRediscoverable` is the
+trustworthy signal because the driver asserts it deliberately.
+
+⚠️ **`IHostConnectivityProbe` is still unconsumed.** `GetHostStatuses()` has no production call site and
+nothing ever writes a `DriverHostStatus` row (the table was re-created in the v3 initial migration, so
+confirm intent before deleting). The separable `OnHostStatusChanged` event is the useful half. Tracked
+as Gitea **#521**.
 
 ## mxaccessgw