docs: Reorganize ADR-0065 structure for improved clarity

- Reframe opening as migration question (clause-based  LINQ-based)
- Move Pros/Cons immediately after Decision Outcome for context
- Consolidate migration content into single section (eliminate repetition)
- Create 'Implementation Sub-Decisions' section for clear hierarchy
- Move alternative options to Appendix to reduce noise
- Establish linear flow: Problem  Decision  Implementation  Migration  Appendix

issue #10456

Author: alzarei