Recognize A-CAWW-TP2-20-COMMON system air conditioners (issue #52)

New '-CAWW-' modelNum token for multi-indoor-unit commercial AC
installs -- these report no oneUiVersion, same as the other RAC/PRAC
boards. Once routed to the existing airconditioner registry, every
resource in the reporter's dump already binds except one new
SAC-specific installation-topology blob, now ignored.

custom_components/localthings/registry/by_type/__init__.py

@@ -113,6 +113,15 @@ def for_device_by_model(model_num: str, description: str) -> Optional[DeviceRegi
     # 'P' sits between the underscore and 'RAC' in that token).
     if key is None and '_RAC_' in (model_num or ''):
         key = 'airconditioner'
+    # System air conditioners (multi-indoor-unit commercial installs, e.g.
+    # A-CAWW-TP2-20-COMMON, issue #52) report no oneUiVersion either and
+    # carry the '-CAWW-' board-family token instead of '_RAC_'/'_PRAC_'.
+    # Same TP1X/TP2X-class resource surface as the room-AC models above
+    # (confirmed by the issue #52 dump binding cleanly against the existing
+    # airconditioner registry once routed here), plus one new SAC-specific
+    # resource (see airconditioner.py's _AC_IGNORED).
+    if key is None and '-CAWW-' in (model_num or '').upper():
+        key = 'airconditioner'
     # Air purifiers (e.g. ARTIK051_TVTL_18K, issue #56) report no
     # oneUiVersion either, and carry the '_TVTL_' board-family token.
     if key is None and '_TVTL_' in (model_num or ''):

custom_components/localthings/registry/capabilities/airconditioner.py

@@ -243,6 +243,11 @@ _AC_IGNORED = [
     '/remotetemperature/vs/0',     # external temp-sensor feed (unset on this unit)
     '/reserverulesets/vs/0',       # opaque hex-encoded schedule reservation blob
     '/welcome/temperature/vs/0',   # welcome-cooling plumbing
+    # System-AC-only (multi-indoor-unit commercial installs, e.g.
+    # A-CAWW-TP2-20-COMMON, issue #52): opaque hex-encoded installation
+    # topology -- indoor/outdoor unit pairing, per-unit serials, MCU info.
+    # Commissioning-time plumbing, not user-actionable appliance state.
+    '/sac/installationinfo/vs/0',
 ]
 
 # Built as bare no-entity caps; folded into the AC registry (not global).