Clean up legacy DB schema: collapse auto-migrations and remove obsolete SQL handlers

[frett]

Summary

• Removes obsolete Room auto-migration JSON schema dumps for DB versions 6–21 (intermediate versions no longer needed since no supported app version targets them)
• Collapses the chain of auto-migrations from 7→8→9→…→22 into a single combined migration (7→22), reducing migration overhead for users upgrading from old installs
• Removes obsolete legacy DB migration SQL constants and handlers for versions 48–57 (v6.0.1 era, no longer reachable)
• Removes obsolete Room auto-migration and schema dump for DB version 6 (v6.0.1)
• Adds v6.3.0 label to the DB version history for clarity

Test plan

• Verify GodToolsRoomDatabaseMigrationIT passes — covers migration paths from old DB versions through to current schema
• Install a build over a sufficiently old install and confirm DB migration succeeds without data loss

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 51.49%. Comparing base (b283b28) to head (3cb69f8).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #4409      +/-   ##
===========================================
+ Coverage    51.02%   51.49%   +0.46%     
===========================================
  Files          449      449              
  Lines        12082    11967     -115     
  Branches      2094     2080      -14     
===========================================
- Hits          6165     6162       -3     
+ Misses        5305     5193     -112     
  Partials       612      612              

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