feat(twincat): opt-in ADS sum-read and /hosts diagnostics bag; refresh TwinCAT backlog (#645, #612)

Sum-read (#310): batches a poll's reads per device into sum commands capped at sumReadMaxItems,
per-item ADS errors mapped per tag, falls back to individual reads when the target refuses the
command. Diagnostics (#314): ADS state, app name, online-change count, task cycle/exec/jitter via
IDriverDiagnostics. Re-implemented against the current raw-byte read path (stranded auto/driver-gaps
commits predate it). Sum-write not ported. Unit tests only; live gate pending a route.

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

CLAUDE.md

@@ -1130,6 +1130,11 @@ host logger factory (wired in `DriverFactoryBootstrap`; the FOCAS and TwinCAT fa
   `DriverHealthChanged.Diagnostics` / proto `has_diagnostics`+`diagnostics`; its digest is in the publish fingerprint).
 - **TwinCAT (#637):** TIME/TOD publish Float64 ms, DATE/DT a UTC DateTime; a tag authored `UDInt` keeps the raw counter
   (and keeps historizing — DateTime is not historized).
+- **TwinCAT (#645, #310/#314):** opt-in ADS sum-read (`useSumRead`, `sumReadMaxItems` default 200; reads raw bytes by index
+  group/offset and decodes with the same codecs as a single read; a target refusing the sum command (overall ADS 1792-1798)
+  flips that device to individual reads, a comms failure does not). `/hosts` diagnostics via `IDriverDiagnostics`
+  (`TwinCAT.AdsState`/`AppName`/`OnlineChangeCnt`/`CycleTimeMs`/`LastExecTimeMs`/`JitterMs`, probe-sampled). Unit-tested only; live
+  gate pending a user-approved route (the presses' routes name the Mac's old VPN IP). Sum-write not ported.
 - **AbLegacy (#636):** `AbLegacyAddress` (in `AbLegacy.Contracts`) is family-aware: PLC-5 `I:`/`O:` indices are OCTAL
   and are emitted to libplctag as decimal (libplctag's `pccc.c` parses decimal only). MicroLogix function files parse
   but read `BadNotSupported`. Indirect `N7:[N7:0]` (#646) is resolved by the driver at read/write time (index re-read