Buildings and levels for the floor map, and make every identifier searchable

The map was one picture of one floor. A second floor was added, the blueprint
changed size, and machines moved, so a position now records WHICH DRAWING its
coordinates belong to.

Buildings and levels (ADR-017). Each level owns its blueprint per theme and its
own native pixel size; assets.mapx/mapy are pixels of assets.levelid, not of the
site. A position whose level is unknown renders "level unknown" and is never
drawn on the default level, because a marker on the wrong floor plan looks
entirely correct while pointing at the wrong place.

Repositioning in bulk: filter by unplaced, needs-review or level, search, place,
confirm. Landmark recalibration solves the transform PER AXIS from landmark
pairs and never from image dimensions - the canvas grew taller without
rescaling, so a dimension-derived scale would stretch Y by 1.57 and be wrong
everywhere. It defaults to a dry run, reports what would land off the drawing,
snapshots before applying, and clears mapverifiedat because a transform is a
guess awaiting review. Snapshots restore, including the level and the review
state, and a restore snapshots first so an undo is undoable.

Search: gaugelabreference was matched only for measuring tools and
maintenancereference was matched nowhere at all, for any asset type, while
Settings happily offers both identifiers on machines and PCs. A tag an operator
is told to record has to be findable or it is a write-only field. USB devices
and printed items were unreachable from search entirely - neither is an asset,
so the generic asset search could not see them and no searcher existed; they
now match on serial, asset tag, label, bin code and gage-lab tag, honouring
isactive, with Settings toggles and result labels to match.

The retired-application rule was half a rule: GET /api/knowledgebase hid
articles whose topic application is retired while global search still returned
them and printed the retired application as the subject. A filter is only real
if every path that reaches the row applies it.

Contract to 0.20.0 (additive): Asset gained levelid and mapverifiedat, Location
gained levelid, and resolve_asset_position returns the levelid belonging to
whichever source supplied the coordinates. The five plugins that write a map
position are re-pinned. The install-list text format gained levelid as a NINTH
field, appended, because the shipped Pascal installer reads fields 0-7 by index.

That installer still compiles in one drawing's dimensions and bundles one
blueprint, so its map is accurate for the default level only; /api/maplevels is
deliberately unauthenticated so it can read both at runtime once rebuilt.
Recorded in PRINTER-INSTALLER.md section 6 along with the other known gaps.

Migration 7d33 converts an existing single-map site into one building and one
default level carrying the old map_* settings, then assigns every placed asset
and location to it. Nothing moves on screen. Old settings rows are kept so a
rollback still finds them. Verified end to end on MySQL 5.6 from a
production-shaped database.

plugins/printers/api/asset_routes.py

@@ -358,6 +358,7 @@ def printer_install_list():
             'iscsf': printer.iscsf,
             'locationname': asset.location.locationname if asset.location else None,
             'mapx': asset.mapx,
+            'levelid': asset.levelid,
             'mapy': asset.mapy,
         })
 
@@ -366,7 +367,7 @@ def printer_install_list():
     # hand-rolled JSON parser. The web map uses the default JSON.
     if request.args.get('format') == 'text':
         fields = ('printerid', 'windowsname', 'vendorname', 'modelnumber',
-                  'hostname', 'ipaddress', 'mapx', 'mapy')
+                  'hostname', 'ipaddress', 'mapx', 'mapy', 'levelid')
         lines = [_text_line(row, fields) for row in rows]
         return Response('\n'.join(lines), mimetype='text/plain')
 
@@ -738,6 +739,7 @@ def create_printer():
         locationid=data.get('locationid'),
         businessunitid=data.get('businessunitid'),
         mapx=data.get('mapx'),
+        levelid=data.get('levelid'),
         mapy=data.get('mapy'),
         notes=data.get('notes')
     )
@@ -819,7 +821,7 @@ def update_printer(printer_id: int):
     # Update asset fields (optional identifiers gated per-type in Settings)
     asset_fields = ['assetnumber', 'name', 'serialnumber', 'gaugelabreference',
                     'maintenancereference', 'statusid',
-                    'locationid', 'businessunitid', 'mapx', 'mapy',
+                    'locationid', 'businessunitid', 'mapx', 'mapy', 'levelid',
                     'notes', 'isactive']
     for key in asset_fields:
         if key in data:
@@ -1035,6 +1037,7 @@ def _get_low_supplies_data():
                 'model': model_number,
                 'location': location_name,
                 'mapx': asset.mapx,
+            'levelid': asset.levelid,
                 'mapy': asset.mapy,
                 'supplies': annotated
             })