Add blog post for config_entry unique_id collision warning (#2467)

* Add blog post for config_entry unique_id collision warning

* Update and rename 2024-11-22-config-flow-unique-id to 2024-11-22-config-flow-unique-id.md

* Update 2024-11-22-config-flow-unique-id.md

* Rename 2024-11-22-config-flow-unique-id.md to 2024-12-19-config-flow-unique-id.md

* Adjust date

* Rename 2025-01-16-config-flow-unique-id.md to 2025-03-01-config-flow-unique-id.md

Author: epenet

blog/2025-03-01-config-flow-unique-id.md

@@ -0,0 +1,15 @@
+---
+author: epenet
+authorURL: https://github.com/epenet
+title: "New checks for config flow unique ID"
+---
+
+### Summary of changes
+
+When a config flow creates an entry with a colliding unique ID, the old entry is currently automatically removed and replaced with the new config entry.
+This can lead to unexpected behavior, and integrations should be adjusted to instead abort the flow.
+
+In case of manual flows, integrations should implement options, reauth, reconfigure to allow the user to change settings.
+In case of non user visible flows, the integration should optionally update the existing entry before aborting.
+
+More details can be found in the [config flow](/docs/config_entries_config_flow_handler#unique-id-requirements) documentation.