feat: warn on destructive and unsupported hypertable migration changes

[sebastian-ederer]

Description

Surface migration changes that destroy data or cannot be applied, instead
of silently skipping or failing them.

Type of Change

• Bug fix (non-breaking change addressing an issue)
• New feature (non-breaking change adding functionality)
• Refactoring
• Documentation
• CI / build / tooling
• Breaking change (fix or feature causing existing functionality to change)

Test Plan

• Unit tests added/updated
• Integration tests added/updated (Testcontainers)
• Existing tests pass (dotnet test)

Checklist

• Code follows the project's coding styles and guidelines
• I have updated the documentation accordingly
• I have added tests to cover my changes
• No new compiler warnings introduced
• Public API changes have XML documentation

[codecov]

Codecov Report

❌ Patch coverage is 98.72611% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
.../Eftdb/Internals/TimescaleMigrationsModelDiffer.cs	0.00%	1 Missing ⚠️
src/Eftdb/TimescaleDbMigrationsSqlGenerator.cs	95.83%	1 Missing ⚠️

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