docs: everything caught up with v1.51.1

A sweep of every document against the shipped behaviour:

- README en+ru: the space dialog no longer claims a background is mandatory
  (draw-by-hand and the saved-plans picker exist; the canvas is square);
  'Show all devices' sections rewritten for the hide-flag world — the
  checkbox, 'Show hidden' ghosts, LQI-yes/light-no; troubleshooting updated.
- ARCHITECTURE: the config schema block still described v1.3 —
  aspect/device_overrides/virtual_devices/1000x1000-per-aspect/legacy-bundle
  fallback, all long gone. Rewritten to the current shape (square canvas,
  markers with hidden, filter_seeded, quotas, signed urls). The WS table
  dropped houseplan/file/set (removed in v1.10.0) and gained
  geometry/repair, layout/delete, files/migrate, files/cleanup,
  content/sign, the plans/list cap.
- UX-MODES: the Devices-tab tool list names the checkbox and the local
  'Show hidden' instead of the retired shared show-all.
- ROADMAP: repair-issues, system_health, floors import, data icon rules,
  click actions, theming and JSON i18n were done releases ago — checked off
  with their versions; the HACS pointer is #9004 (bot closed #8995).
- STATUS: SSH port is 22222 and the HA config root is
  /mnt/data/supervisor/homeassistant (/config does not exist there); the
  key lives in houseplan/.secrets; the PAT note reflects the fine-grained
  token; the feature surface gained the v1.42-v1.51 era.
- DEVELOPMENT: deploy instructions with the real port, path and cache
  busting.
- The owner's product description (user folder) refreshed the same way:
  square canvas, hide flags, the yellow principle.

docs/UX-MODES.md

@@ -59,8 +59,10 @@ Header in View: space tabs, device count, zoom cluster. Nothing else.
 - Icon dragging (ONLY here). Click on a device opens the **edit dialog directly**
   (binding, name, icon, size/angle, display badge/ripple + colors, tap override,
   model/link/description/PDFs, room).
-- + add device/entity/virtual, hide device, ↺ reset layout, 👁 show-all (curation
-  tool), ⬡ icon rules.
+- + add device/entity/virtual, the "Hide device from plan" checkbox (since
+  v1.51.0 the one hiding mechanism, docs/FILTERING.md), ↺ reset layout,
+  👁 "Show hidden" (local editor tool; replaced the shared show-all toggle),
+  ⬡ icon rules.
 
 ## Deprecations decided
 
@@ -85,7 +87,7 @@ Header in View: space tabs, device count, zoom cluster. Nothing else.
   edit interactions/buttons (biggest UX win, smallest surface).
 - **It.2 — Plan tab:** move markup tools + space dialogs + labels drag + openings
   editing under Plan; colored frame indicator.
-- **It.3 — Devices tab:** drag + direct-edit click + curation tools under Devices.
+- **It.3 — Devices tab:** drag + direct-edit click + filtering tools under Devices.
 - **It.4+:** follow-up features 1–5 above, each its own release.