Retire the legacy Machine model (ADR-001 cutover)

The asset/computer model is now the single source of truth. Remove the Machine
instance layer end to end:

- Delete models Machine, MachineStatus, PCType, MachineRelationship,
  InstalledApp, PrinterData; keep MachineType (models.machinetypeid still
  references it).
- Delete the /api/machines, /api/statuses, /api/pctypes blueprints and the
  legacy /api/printers/legacy (PrinterData) blueprint.
- Drop the deprecated communications.machineid column and its FK.
- Migration 7c01 drops tables machines, machinestatuses, pctypes,
  machinerelationships, installedapps, printerdata (idempotent).
- Fix remaining readers (applications install counts) to ComputerInstalledApp.
- Frontend: remove dead machinesApi/statusesApi/pctypesApi wrappers; repoint
  the PC Types settings page at computer types.

143 tests pass; all asset/computer/dashboard/report/collector endpoints 200.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

shopdb/core/api/applications.py

@@ -66,7 +66,8 @@ def list_applications():
             }
         else:
             app_dict['supportteam'] = None
-        app_dict['installedcount'] = app.installed_on.filter_by(isactive=True).count()
+        app_dict['installedcount'] = ComputerInstalledApp.query.filter_by(
+            appid=app.appid, isactive=True).count()
         data.append(app_dict)
 
     return paginated_response(data, page, per_page, total)
@@ -96,7 +97,8 @@ def get_application(app_id: int):
     else:
         data['supportteam'] = None
     data['versions'] = [v.to_dict() for v in app.versions.filter_by(isactive=True).order_by(AppVersion.version.desc()).all()]
-    data['installedcount'] = app.installed_on.filter_by(isactive=True).count()
+    data['installedcount'] = ComputerInstalledApp.query.filter_by(
+        appid=app.appid, isactive=True).count()
 
     return success_response(data)