chore: Add migration script to backfill user actions

[DrewAire]

Record of script being run during release on 23rd July 2026. Added to a separate folder in DatabaseUpgrader so it's not run automatically, and fully commented out just in case.

[github-actions]

SQL Risks Found

src/Dfe.PlanTech.DatabaseUpgrader/RunOnceMigrationScripts/20260723_GenerateUserActionsForPreExistingSubmissions.sql

+-------------------------------------------------+
|                   SQLCHECK                      |
+-------------------------------------------------+
> RISK LEVEL    :: ONLY MEDIUM AND HIGH RISK ANTI-PATTERNS
> SQL FILE NAME :: src/Dfe.PlanTech.DatabaseUpgrader/RunOnceMigrationScripts/20260723_GenerateUserActionsForPreExistingSubmissions.sql
> COLOR MODE    :: DISABLED
> VERBOSE MODE  :: DISABLED
> DELIMITER     :: ;
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==================== Results ===================

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SQL Statement at line 1: /* how to use this script ====================== - add "--" to the "/ *" under
block 1 to activate it (line 27) - run block 1 to generate submission data and
user actions - confirm data looks reasonable - tempdatacount should be ≤
realdatacount (we ignore submissions with no responses) -
creation/updateuseractioncount should equal tempdatacount -
completionuseractioncount will most likely be less if there are many submissions
in progres - mats and sats should not have any missing mat establishment ids.
schools are expected to have lots missing. - remove the "--" you added from the
start of block 1 - add "--" to the "/ *" under block 2 to activate it (line 276)
- run block 2 to add user actions to the database and associate them with
submissions - confirm the associated establishment names look right - change
"rollback tran" at the end of block 2 to "commit tran";
[src/Dfe.PlanTech.DatabaseUpgrader/RunOnceMigrationScripts/20260723_GenerateUserActionsForPreExistingSubmissions.sql]: (MEDIUM RISK) (PHYSICAL_DATABASE_DESIGN ANTI-PATTERN) Imprecise Data Type
[Matching Expression: real at line 8]


-------------------------------------------------
SQL Statement at line 116: select count(*) as realdatacount from dbo.submission;
[src/Dfe.PlanTech.DatabaseUpgrader/RunOnceMigrationScripts/20260723_GenerateUserActionsForPreExistingSubmissions.sql]: (MEDIUM RISK) (PHYSICAL_DATABASE_DESIGN ANTI-PATTERN) Imprecise Data Type
[Matching Expression: real at line 116]


==================== Summary ===================
All Anti-Patterns and Hints  :: 2
>  High Risk   :: 0
>  Medium Risk :: 2
>  Low Risk    :: 0
>  Hints       :: 0