Import update (#10188)

* Add field to "update" existing records

* Ensure the ID is first

* Prevent editing of "ID" field

* Extract db instance

* Bump API version

* Prevent edit of "id" field

* Refactoring

* Enhanced playwright tests for data importing

* Update docs

* Update src/backend/InvenTree/importer/models.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Update src/frontend/src/forms/ImporterForms.tsx

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Fix silly AI mistake

* Fix for table pagination

- Ensure page does not exceed available records

* Bug fix for playwright test

* Add end-to-end API testing

* Fix unit tests

* Adjust table page logic

* Ensure sensible page size

* Simplify playwright test

* Simplify test again

* Tweak unit test

- Importing has invalidated the BOM?

* Adjust playwright tests

* Further playwright fixes

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

docs/docs/settings/import.md

@@ -76,3 +76,37 @@ Each individual row can be imported, or removed (deleted) by the user. Once all
 ### Import Completed
 
 Once all records have been processed, the import session is considered complete. The import session can be closed, and the imported records are now stored in the database.
+
+## Updating Existing Records
+
+The data import process can also be used to update existing records in the database. This requires that the imported data file contains a unique identifier for each record, which can be used to match the records in the database.
+
+The basic outline of this process is:
+
+1. Export the existing records to a CSV file.
+2. Modify the CSV file to update the records as required.
+3. Upload the modified CSV file to the import session.
+
+!!! note "Mixing Creation and Update"
+    It is not possible to mix the creation of new records with the updating of existing records in a single import session. If you wish to create new records, you must create a separate import session for that purpose.
+
+### Create Import Session
+
+!!! note "Admin Center"
+    Updating existing records can only be performed when creating a new import session from the [Admin Center](./admin.md#admin-center).
+
+Create a new import session, and ensure that the *Update Existing Records* option is selected. This will allow the import session to update existing records in the database.
+
+{{ image("admin/import_session_create_update.png", "Update existing records") }}
+
+### Map Data Fields
+
+When mapping the data fields, ensure that the `ID` field is correctly mapped to the corresponding column in the file:
+
+{{ image("admin/import_select_id.png", "Update existing records") }}
+
+### Process Data
+
+When processing the data, each row will be matched against an existing record in the database. If a match is found, the existing record will be updated with the new data from the imported file.
+
+{{ image("admin/import_update_process.png", "Update existing records") }}