Fix consolidated migration history and SQLite collation rebuilds

[jogibear9988]

Consolidated baselines can mark older migrations as applied, but the v13 runner still executed those steps from its precomputed plan. Recheck scope-specific history before each step, support history changes during downgrades, and avoid recording a self-recording baseline twice.

SQLite rebuilds now preserve declared column collations and expose them through metadata. Explicit collation changes retain constraints and roll back on uniqueness violations. Unsupported index-level collations still fail before replacing the table.

Adds regression coverage for scope isolation, transaction modes, rollback, collation parsing and comparison behavior, atomic SQLite identity/key creation, column quoting, and SQL Server/PostgreSQL renamed-table key naming. Updates the 12.1-to-13 migration guide with supported upgrade patterns.

Validation:

• Regression tests added before fixes: 13 failed, 5 passed; all 18 now pass.
• Full solution build passed.
• Unit suite: 95 passed, 0 skipped.
• SQLite suite: 223 passed, 0 skipped.
• New SQL Server/PostgreSQL rename tests were attempted with unchanged configuration. Both failed during connection setup because the configured instances were unavailable locally; provider CI validation remains required.

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