Add README, customization snapshot, and snapshot/restore tooling

Provisioning now restores all GUI customizations on reset+reprovision:

- create_pod_espocrm.sh: deploy the version-controlled espocrm-custom/ tree
  (CTag entity, layouts, i18n, clientDefs, custom views, custom CSS) into the
  pod, then chown www-data and rebuild. Replaces the earlier inline CSS-only
  step. Adds a live-phase cache rebuild so customizations and the client
  cacheTimestamp are refreshed on every run.
- espocrm-custom/: snapshot of custom/ and client/custom/ (source of truth).
- snapshot_espocrm_custom.sh: refresh the snapshot from a running pod.
- readme.md: usage, first-time host setup, image-update and reset workflows.
- Include the task/instruction notes and plan.md for reference.

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

espocrm-custom/custom/Espo/Custom/Resources/metadata/clientDefs/Account.json

@@ -0,0 +1,20 @@
+{
+  "relationshipPanels": {
+    "agentur": {
+      "layout": null,
+      "selectPrimaryFilterName": null
+    },
+    "cAgentur": {
+      "layout": null,
+      "selectPrimaryFilterName": null
+    },
+    "tags": {
+      "layout": null,
+      "selectPrimaryFilterName": null
+    },
+    "cTags": {
+      "create": false,
+      "rowActionsView": "custom:views/record/row-actions/tags-unlink-only"
+    }
+  }
+}