nixos/home: Separate router storage and uplinks

Give `river` a dedicated RDMA VF and two RSTP trunk attachments.
Keep client services on the router VIPs and carry Digiweb VLANs
over both switch paths.

Set VF trust, multicast reception, bridge MAC and ARP behavior for
local switching. Wait for Kea interface readiness and apply RSTP
costs through `mstpd` despite port-registration and rename races.

Load `palace`'s RAID module in the initrd. Record RouterOS and
RouterBOOT upgrades and validate port, carrier and switch outages.

Document the deployed architecture, interface handoffs and recovery
procedures. Add physical socket maps, NIC capacities and cable
connections alongside the logical topology and failover checks.

docs/sites/home/diagrams/README.md

@@ -0,0 +1,21 @@
+# Home network diagrams
+
+`switch-ports.json` holds the socket inventory, NIC capacities and cable endpoints. Regenerate
+`switch-panels.svg` and the cable table in `../switches.md` from the repository root:
+
+```sh
+python3 docs/sites/home/diagrams/render-switch-panels.py
+```
+
+The renderer uses only the Python standard library. Socket geometry and schematic cable routing
+live in the renderer. Keep the inventory and routing together when adding a connection.
+
+`home-fabric.mmd` is the Mermaid source for the logical fabric diagram. Render it with Mermaid
+CLI (the checked-in SVG was rendered with Mermaid 11.12.0):
+
+```sh
+mmdc -i docs/sites/home/diagrams/home-fabric.mmd -o docs/sites/home/diagrams/home-fabric.svg
+```
+
+Check rendered SVGs visually after editing. Both diagrams are checked in so Markdown viewers
+can show them without Mermaid support.