fix(mtconnect): back off a /sample re-baseline that resolved nothing; scope Test Connect to the configured device

Driver.MTConnect-001 (Medium): StreamVerdict.Reopen reset the reconnect ladder
unconditionally. The InvalidDataException catch that routes an Agent OUT_OF_RANGE
to a /current re-baseline also catches an unparseable chunk and an over-sized
multipart part - neither of which a re-baseline can resolve - so the pump reopened
and failed with no delay at any point: two HTTP requests and one Warning per
iteration, forever. The Reopen arm now uses the same discriminator the transient
arm does (did THIS connection deliver a chunk?), so a buffer roll behind a working
stream still reopens instantly while a re-baseline that resolved nothing advances
BackoffFor.

Driver.MTConnect-002 (Medium): MTConnectDriverProbe requested {AgentUri}/probe
while MTConnectAgentClient requests {AgentUri}/{DeviceName}/probe, so a mistyped or
since-renamed deviceName showed GREEN on Test Connect and then Faulted the driver
at InitializeAsync (an unknown device path answers MTConnectError under HTTP 200).
The probe's minimal DTO now reads deviceName - the rule is 'which keys compose the
URL', not 'which keys are cheap to read'.

Driver.MTConnect-008 (Low): corrected two stale claims that a since-changed
RawBrowseCommitMapper invalidated (see Driver.MTConnect-003, which remains open and
belongs in AdminUI), and made DiscoverAsync log the options snapshot it
deliberately read once instead of the field.

Tests: 538 pass (534 base + 4 new, each red before its fix); AdminUI.Tests 1466 pass.

docs/drivers/MTConnect.md

@@ -167,9 +167,11 @@ universal browser commits and the key the driver resolves reads/subscribes
 against. `MTConnectTagConfigModel.FromJson` (the AdminUI typed editor) tries
 three spellings in order — `fullName` → `dataItemId` → `address` — and takes
 the first non-blank one, normalising onto `fullName` on save. `address` is
-accepted because that's the field name `RawBrowseCommitMapper` writes for a
-driver with no typed editor path, so a browse-committed tag stays readable
-even before the editor round-trips it.
+accepted because that is the field name `RawBrowseCommitMapper` writes for a
+driver with no typed-editor branch of its own — MTConnect has had such a
+branch since Gitea #536 and now commits under `fullName`, but blobs committed
+before it, and hand-authored/CSV/API blobs, still carry `address` and must
+stay readable.
 
 ### Coercion-type precedence
 
@@ -192,6 +194,16 @@ into) is resolved in this order, first non-null wins:
    (category/type/units/representation → `DriverDataType`).
 4. `DriverDataType.String` — the coercion that cannot fail.
 
+> ⚠️ **Step 3 does not currently rescue a browse-committed tag.** `RawBrowseCommitMapper`'s
+> MTConnect branch emits a whole `MTConnectTagConfigModel`, whose `ToJson()` always writes
+> `dataType` from a field defaulting to `String` — a non-blank authored type, so step 1 wins
+> and step 3 is never consulted. The raw tag's OPC UA `DataType` meanwhile *is* taken from the
+> browsed leaf's inferred type (`RawBrowseCommitMapper.MapLeaf` → `MapDataType`), so a browsed
+> `SAMPLE` lands as a `Double` node whose driver coerces the observation to text. Fix belongs in
+> the commit mapper (forward the leaf's `DriverDataType` into the model, as the AbCip / TwinCAT /
+> FOCAS branches already do). Recorded as `Driver.MTConnect-003` in
+> [`code-reviews/Driver.MTConnect/findings.md`](../../code-reviews/Driver.MTConnect/findings.md).
+
 ### Quality mapping
 
 `UNAVAILABLE` — MTConnect's one explicit "I have no value" sentinel — maps to