Match SQLite GUID defaults to parameter storage without converting legacy defaults

[jogibear9988]

SQLite GUID parameters are stored as blobs, but CLR Guid column defaults were rendered as text. A defaulted child key therefore failed foreign-key validation against an explicitly inserted parent with the same GUID, blocking KCC's tenant migration.

Render new Guid defaults using the same Guid.ToByteArray() representation as parameters. Preserve existing GUID default SQL as RawSql during metadata inspection so unrelated rebuilds retain legacy text values and defaults without silently changing storage classes. Existing mixed-format data still requires an explicit data migration.

Eight tests were added before the fix: six failed and two passed. All eight now pass across Microsoft.Data.Sqlite and System.Data.SQLite, covering empty/nonempty GUIDs, byte order, foreign keys, populated-table backfills, rebuilds, and legacy text defaults.

Validation:

• Full solution build passed; 176 unit and 229 SQLite tests passed locally, with no skips.
• All 12 database/unit CI matrix jobs and complete-test-coverage verification passed.
• Downstream KCC full build passed after the required v13 consumer adaptations. All six focused migration checks passed, including the complete SQLite and SQL Server migration chains and populated/legacy schema transitions.
• KCC unit suite: 763 passed, 0 failed, 3 skipped. Other tests: 80 passed, 0 failed, 2 skipped.
• KCC full integration run: 1,662 passed, 489 failed, 8 skipped. One test used the wrong migration-history scope; its consumer-side correction passed a focused rerun. Latest per-test outcomes are 1,663 passed, 488 failed, 8 skipped. The full integration suite was not rerun after that test-only correction.
• Remaining integration failures: 486 configured Oracle authentication/connection failures and two unrelated filter-fixture assertions caused by existing rows. Database configuration, integrity checks, and unrelated test behavior were left unchanged. KCC adaptations are in the separate consumer worktree, not this PR.

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