feat(mtconnect): warn at Test Connect and deploy when SampleCount >= the Agent bufferSize (#825)

Parse the /probe Header bufferSize; MTConnectDriverProbe reads sampleCount
(default 1000) and answers Ok with a WARNING message (amber chip in the
Test Connect button); InitializeAsync logs the same Warning and exposes
agentBufferSize on the diagnostics bag. Live-checked against the shared
cppagent fixture (bufferSize 16384).

docs/drivers/MTConnect.md

@@ -372,6 +372,11 @@ Degraded across further re-baselines until a chunk is delivered. Values keep flo
 off the re-baselines and `LastSuccessfulRead` keeps advancing — each `/current` is the
 Agent answering — so the comms-loss watchdog does not reconnect-loop a configuration
 problem. Size `SampleCount` below the Agent's `bufferSize` (in the `/probe` header).
+**It is caught before it happens (#825):** the `/probe` header's `bufferSize` is parsed
+(`MTConnectProbeModel.BufferSize`, advisory — missing/malformed is null, never a parse failure); **Test
+Connect** reads `sampleCount` (default 1000 when absent) and answers Ok **with a warning** (an amber
+"OK with warning" chip showing the text) when it is at or above the buffer, and the driver's **initialize**
+(every deploy) logs the same Warning and puts `agentBufferSize` on the `/hosts` diagnostics bag.
 
 **An Agent `instanceId` change means the Agent restarted**, and is checked
 **before** the sequence-gap check (a restart also usually trips the gap, so