R-50 Phase A: host-install v1.19.0 island default + hub version sync

- felhom-host-install v1.19.0: portless vmbr9 island bridge, appliance binds
  local_api on 169.254.253.1:8443, writes island_bridge/island_guest_addr,
  pins lan_resolver.host_ip to the LAN IP (Finding-1). --no-island opt-out.
- hub hostInstallVersion 1.16.0 -> 1.19.0 (F-1 sync). hostinstall_gates PASS.
- Pairs with agent v0.96.0 (attaches guest net1). byo unchanged.
Coupling: island install requires agent >= 0.96.0 (vouch first).

hub/CHANGELOG.md

@@ -1,5 +1,13 @@
 # Felhom Hub — Changelog
 
+## v0.73.2 — sync `hostInstallVersion` → 1.19.0 (R-50 island host-install) (2026-07-25)
+
+`hostInstallVersion` (the script version the operator customer page's install-command generator
+advertises) bumped 1.16.0 → **1.19.0** to match `felhom-host-install v1.19.0` (R-50 island default). The
+`hostinstall_gates.py` F-1 gate requires the two move together; this also clears the pre-existing
+1.16.0↔1.18.0 drift. Render test (`render_test.go`) confirms the value reaches the page. No behaviour
+change beyond the advertised version string.
+
 ## v0.73.1 — allowlist `disk_health_degraded` (controller v0.169.0 disk-health) (2026-07-24)
 
 Adds `disk_health_degraded` to `allowedEventTypes` so the controller's per-disk SMART degradation