fix(s7): numeric TSAP loads in form, shared TSAP conflict error, Test Connect read detects PUT/GET disabled, pin Int32 ms rounding (#632 #638)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

docs/drivers/S7.md

@@ -82,6 +82,13 @@ malformed TSAP fails to load rather than silently falling back to the slot-deriv
 the three set the connection is built exactly as before. The override applies to the driver, the AdminUI
 Test Connect probe and the AdminUI S7 driver form (Connection type / Local TSAP / Remote TSAP fields).
 
+### Test Connect and PUT/GET
+
+After the handshake, Test Connect reads 2 bytes from `MB0`. A CPU with PUT/GET disabled (the S7-1200/1500
+default) completes the handshake but denies every read, so the probe fails with an actionable "enable
+PUT/GET communication" message instead of a false green tick. A CPU that merely rejects that address (no
+`MB0`) still passes — the connection is fine; any other read fault fails the probe with its message.
+
 ## Address forms
 
 Addresses use Siemens TIA-Portal / STEP 7 Classic syntax, parsed by
@@ -151,6 +158,8 @@ These add no new OPC UA data types — they map onto existing ones:
 | `Time` | **Int32 ms** (signed duration) | Int32 ms | outside the Int32 range |
 | `S5Time` | **Int32 ms** | 2-bit time base (10 ms / 100 ms / 1 s / 10 s) + 3 BCD digits | above 9 990 000 ms, negative, or not exactly representable (resolution is 10 ms up to 9 990 ms, then coarser) — **never rounded** |
 
+A fractional millisecond `Double` is rounded to the nearest whole millisecond (banker's rounding), exactly
+as the driver does for every other Int32 tag write; only values off the S5TIME time-base grid are refused.
 A write of a `TimeSpan` is also accepted for `Tod` / `Time` / `S5Time`. A PLC buffer the codec cannot
 decode — an uninitialised (all-zero) `Dtl`, a non-BCD `S5Time` digit, a `WString` whose current length
 exceeds its reserved length — reads `BadOutOfRange` for that tag only, without degrading driver health