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/layouts/Opportunity/kanban.json

@@ -0,0 +1,17 @@
+[
+    {
+        "name": "name",
+        "link": true
+    },
+    {
+        "name": "account"
+    },
+    {
+        "name": "amount",
+        "align": "right",
+        "isLarge": true
+    },
+    {
+        "name": "cLeadQuelle"
+    }
+]