add Entra device identity to computers and Azure/Thor import sources

PC records now carry Entra/Azure device identity so imported machines keep a durable link back to their directory object instead of matching on hostname alone. Adds azuredeviceid, azureobjectid, and azuredevicecategory to the Computer model with matching migrations, surfaces them read-only in PCDetail as an Entra Device Info card, and lets PCForm edit the device id directly. The computers plugin registers a machineassetnumber import hook that reconciles PC-to-machine links during bulk import and warns on unresolved or conflicting relationships.

Adds importsources adapters that normalize Azure device-group and Thor PC inventory exports into canonical ShopDB CSVs via hostname alignment, exposes register_import_hook and RowWarning on the shopdb.api contract surface (contract 0.21.0), and refreshes the Import Site Assets page with clearer source instructions. Includes reconcile_locations maintenance script and coverage for the new import paths.

.dockerignore

@@ -0,0 +1,23 @@
+# Keep the build context lean and prevent host artifacts from clobbering
+# in-image installs. node_modules is platform-specific: copying the host's
+# (Windows) tree over the container's `npm ci` breaks rollup's native binary.
+**/node_modules
+frontend/dist
+frontend/src/.plugins-staged
+frontend/src/router/routes.gen.js
+
+# Python caches and virtualenvs
+**/__pycache__
+**/*.pyc
+.venv
+venv
+
+# Local dev and VCS noise
+.git
+.gitignore
+*.log
+.env.local
+
+# Installer build artifacts (not part of the app image)
+installer-arch-dev/build
+installer-arch-dev/dist