Phase 7A: wire ADR-001 asset position contract surface

Lock the position-resolution columns from ADR-001 in code so
resolve_asset_position's relationship walk activates.

Schema
- Asset.mapleft -> Asset.mapx, Asset.maptop -> Asset.mapy
- Location.mapx / Location.mapy added (fallback for priority 3 of the
  ADR-001 resolution chain)
- AssetRelationship.label (free-text nuance per ADR-001)
- AssetRelationship.inheritsposition (bool, server_default true, controls
  whether the resolved-position walk follows the edge)
- RelationshipType.propagatesthroughid (self-FK; sibling-propagation rail)

Seeds
- Three canonical ADR-001 relationship types created idempotently:
  partof, controls, connectedto
- controls.propagatesthroughid wired to partof (partof + connectedto stay
  null per ADR-001 table). Both via Alembic migration AND CLI seed command
  so a fresh test fixture and a sister-site deploy both end up correct.
- Legacy connection types (Serial Cable, Direct Ethernet, USB, WiFi,
  Dualpath) retained for backward compat with pre-1.0 relationship rows.

Resolver
- shopdb.api.resolve_asset_position now walks inheritsposition=true edges
  of type partof (then controls), recursively, depth-capped at 3 with
  visited-set cycle protection. Inactive edges + non-inheritable types
  are skipped. Falls through to the existing location fallback when the
  walk yields nothing.

Tests
- 11 new test_api_namespace cases cover: partof walk, controls-after-
  partof ordering, connectedto skipped, inheritsposition=false skipped,
  recursion, cycle break, depth-3 cap, self-beats-related, related-beats-
  location, inactive-edge skip.
- 111 tests pass. Naming/style check green.

Migration
- migrations/versions/7a01_adr001_position_contract.py:
  - alter_column renames on assets (no data loss)
  - add_column on locations + relationshiptypes + assetrelationships
  - idempotent seed of three ADR types + propagation FK wire-up
  - downgrade reverses + best-effort deletion of seeded types that have
    no FK refs

Backend rename (mapleft/maptop -> mapx/mapy)
- shopdb/core/api/assets.py
- plugins/{computers,equipment,network,printers}/api/...
- scripts/migration/migrate_assets.py
- Legacy Machine model + machines API + import_from_mysql.py UNCHANGED
  (per ADR-001 Machine retires; not part of the asset contract)

Frontend rename
- frontend/src/components/ShopFloorMap.vue
- frontend/src/views/{MapEditor.vue, pcs/{PCDetail,PCForm}.vue,
  printers/{PrinterDetail,PrinterForm}.vue,
  machines/{MachineDetail,MachineForm}.vue,
  network/NetworkDeviceForm.vue}
- Form field labels + v-model bindings + computed flags switched in
  lockstep with the backend.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/migration/migrate_assets.py

@@ -73,11 +73,11 @@ def migrate_machine_to_asset(machine_row, asset_type_id, target_session):
         INSERT INTO assets (
             assetid, assetnumber, name, serialnumber,
             assettypeid, statusid, locationid, businessunitid,
-            mapleft, maptop, notes, isactive, createddate, modifieddate
+            mapx, mapy, notes, isactive, createddate, modifieddate
         ) VALUES (
             :assetid, :assetnumber, :name, :serialnumber,
             :assettypeid, :statusid, :locationid, :businessunitid,
-            :mapleft, :maptop, :notes, :isactive, :createddate, :modifieddate
+            :mapx, :mapy, :notes, :isactive, :createddate, :modifieddate
         )
     """), {
         'assetid': machine_row['machineid'],
@@ -88,8 +88,8 @@ def migrate_machine_to_asset(machine_row, asset_type_id, target_session):
         'statusid': machine_row.get('statusid', 1),
         'locationid': machine_row.get('locationid'),
         'businessunitid': machine_row.get('businessunitid'),
-        'mapleft': machine_row.get('mapleft'),
-        'maptop': machine_row.get('maptop'),
+        'mapx': machine_row.get('mapx'),
+        'mapy': machine_row.get('mapy'),
         'notes': machine_row.get('notes'),
         'isactive': machine_row.get('isactive', True),
         'createddate': machine_row.get('createddate', datetime.utcnow()),