HARMONIZE. (docs) Merge AGENTS.md and QWEN.md with conflict resolution

AGENTS.md harmonization:
- Replaced 612-line dual-document (UMA2 + Codex) with 384-line unified version
- Resolved language conflict: English default (was Russian vs English)
- Removed outdated Python rules (Typer, plumbum, uv/ruff/mypy)
- Added TypeScript/Dart preferences matching actual tech stack
- Added MathMagic-specific architecture rules
- Added technical debt awareness section
- Added agentic development best practices
- Added decision log appendix with conflict resolutions

QWEN.md updates:
- Added cross-references to AGENTS.md sections
- Updated git workflow with pre-commit checklist
- Updated code style with DRY principle
- Clarified ConPort usage summary

Key decisions documented:
1. Language: English default (aligns with output-language.md)
2. Python rules: Removed (project uses TypeScript/Dart)
3. Conflict resolution hierarchy added to appendix

Files changed:
- AGENTS.md: 612 lines → 384 lines (37% reduction, harmonized)
- QWEN.md: Added cross-references, updated sections

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

Author: xronocode