docs: measured PP link math (H=5120 verified, 20.5 MB/ubatch wire), NIC inventory

- Ethernet Bandwidth Math: new section 0 with live measurements
  (iperf 281-294 MB/s, ping RTT both paths, prefill 457.9 t/s at
  2.5GbE, per-ubatch wire 20.5 MB, 98k KV snapshot 3.45 GB blocking
  the slot 13.6 s, validated link-speed model: 386/458/505 t/s)
- System specs: NIC tables for both boxes; the 1 GbE USB-C adapter on
  the claw was silently routing the RPC path (unplugged 2026-08-17)
- PP Deployment: fix hidden-state size (10 KiB/direction, H=5120) and
  RTT-vs-bandwidth claim (decode RTT-bound; prefill+snapshot BW-bound)

docs/Dankclaw System Specs.md

@@ -66,6 +66,19 @@ The NPU shares the 30 GiB unified pool. FLM allocates roughly half of system RAM
 |------------|------|------|-------|------|
 | / (nvme0n1p2) | 1.9T | 661G | 1.1T | 38% |
 
+### Network
+
+| Interface | Type | Speed | IP | Notes |
+|-----------|------|-------|----|-------|
+| eno1 | onboard | 2500 Mb/s (2.5 GbE) | 192.168.0.143 (DHCP) | Carries the RPC path to Dankserver since 2026-08-17. Default route via 192.168.0.1. |
+| enx00e04cc2e1e5 | USB-C to Ethernet adapter | 1000 Mb/s | 192.168.0.116 | UNPLUGGED 2026-08-17. While present, the route to 192.168.0.235 went through this adapter (lower route metric), so all RPC traffic was capped at 1 GbE. See [[Pipeline Parallelism/Ethernet Bandwidth Math]] section 0. |
+| docker0 | bridge | - | 172.17.0.1 | Usually down. |
+
+The L2 gateway/switch at 192.168.0.1 (MAC f0:4b:8a:65:c5:40) is at
+least 2.5 GbE-capable. Whether it is 10G-capable is unverified — check
+the device itself before buying 10G USB-C adapters; otherwise a direct
+cable between claw and server is required for 10G.
+
 ### OS and Software
 
 | Property | Value |