Completes the split: `nodes` now holds only how a device is drawn on one
canvas, and every device fact reaches the API from the inventory row.
- The device columns are removed from `nodes` (SQLite table rebuild, the
same shape as the existing device_inventory and canvas_state rebuilds).
The drop is skipped, and logged, while any non-furniture node is still
unlinked: those columns are the last copy of that node's facts. The
backfill therefore reads them with raw SQL — by the time it runs, the
model no longer declares them.
- The status checker iterates devices, not nodes: one check per device
however many canvases draw it, writing `status_live` / `last_seen` /
`response_time_ms` on the row. `/ws/status` messages carry `device_id`
and the node ids they light up. Hidden devices are not probed.
- Readers repointed: scanner (last_scan lands on the row), proxmox (its
node tier collapses into the inventory tier, keeping only the cluster
handles), zigbee/zwave (one property refresh serves every canvas), rack
inventory, liveview, stats, node dedupe.
- `POST /scan/pending` merges into the row that already describes the host
instead of minting a second one — one device is one row, whichever way it
was documented.
- Standalone keeps parity: the canvas blob gains `devices`, split on save
and hydrated on load. A blob written before the split still reads.
The rack inventory had a related bug: a mount that names a node explicitly
printed the mount's device rather than the pinned node's. It now reads the
node's own row.
Tests that built a node with device columns are ported to the link; where a
behaviour genuinely moved (properties refresh once on the row, last_scan is
the device's) the assertion moved with it rather than being dropped.
ha-relevant: yes