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>

frontend/src/views/network/NetworkDeviceForm.vue

@@ -169,20 +169,20 @@
           <legend>Map Position (Optional)</legend>
           <div class="form-row">
             <div class="form-group">
-              <label for="mapleft">Map X Position</label>
+              <label for="mapx">Map X Position</label>
               <input
-                id="mapleft"
-                v-model.number="form.mapleft"
+                id="mapx"
+                v-model.number="form.mapx"
                 type="number"
                 class="form-control"
                 min="0"
               />
             </div>
             <div class="form-group">
-              <label for="maptop">Map Y Position</label>
+              <label for="mapy">Map Y Position</label>
               <input
-                id="maptop"
-                v-model.number="form.maptop"
+                id="mapy"
+                v-model.number="form.mapy"
                 type="number"
                 class="form-control"
                 min="0"
@@ -251,8 +251,8 @@ const form = ref({
   rackunit: '',
   ispoe: false,
   ismanaged: false,
-  mapleft: null,
-  maptop: null,
+  mapx: null,
+  mapy: null,
   notes: ''
 })
 
@@ -335,8 +335,8 @@ async function loadDevice() {
     form.value.statusid = data.statusid || ''
     form.value.locationid = data.locationid || ''
     form.value.businessunitid = data.businessunitid || ''
-    form.value.mapleft = data.mapleft
-    form.value.maptop = data.maptop
+    form.value.mapx = data.mapx
+    form.value.mapy = data.mapy
     form.value.notes = data.notes || ''
 
     // Network device specific
@@ -376,8 +376,8 @@ async function submitForm() {
       rackunit: form.value.rackunit || null,
       ispoe: form.value.ispoe,
       ismanaged: form.value.ismanaged,
-      mapleft: form.value.mapleft,
-      maptop: form.value.maptop,
+      mapx: form.value.mapx,
+      mapy: form.value.mapy,
       notes: form.value.notes || null
     }