Squash migration files up to v1.5.5

[FelixMalfait]

Summary

Squash 178 migration files (up to v1.5.5) into 2 consolidated migrations to significantly improve migration performance.

Changes

• Consolidate 169 common migrations into a single squashed migration
• Consolidate 11 billing migrations into a single squashed migration
• Remove 178 files (86% reduction: 207 → 29 migration files)
• Make FK_47a6c57e1652b6475f8248cff78 constraint DEFERRABLE INITIALLY DEFERRED to fix self-referencing foreign key issues
• Preserve all 27 post-v1.5.5 migrations (25 common + 2 billing)

Impact

• ✅ 2-3x faster migration execution for new installations
• ✅ Faster dev environment setup (database resets)
• ✅ Both IS_BILLING_ENABLED=false and true modes tested and verified
• ✅ All critical tables and constraints verified

Testing

• Tested migrations from scratch with billing disabled (26 migrations)
• Tested migrations from scratch with billing enabled (29 migrations)
• Verified all critical tables exist (workspace, user, fieldMetadata, etc.)
• Verified all 7 billing tables created correctly when enabled
• Confirmed DEFERRABLE constraint is properly applied

Files Changed

• 180 files changed: +443 insertions, -6,462 deletions
• Net reduction: -6,019 lines of code

[github-actions]

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