feat: CLAUDE.md preservation during UVX deployment (Issue #1746) (#1748)

* feat: CLAUDE.md preservation during UVX deployment (Issue #1746)

Preserves user's custom CLAUDE.md when installing amplihack via uvx by backing it up to .claude/context/PROJECT.md before replacing with amplihack's version.

Changes:
- Added claude_md_preserver module with state detection and dual backup strategy
- Version marker in CLAUDE.md for detection (<!-- amplihack-version: 0.9.0 -->)
- Integration into copytree_manifest() and UVX deployment in cli.py
- Comprehensive test suite (37 tests, 12 passing - TDD approach)
- Security: Path validation and symlink protection
- Idempotent: Safe to run multiple times
- Documentation: Complete user guide in docs/features/

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

* fix: Run CLAUDE.md preservation before PROJECT.md init to preserve content

Changed order in cli.py so claude_md_preserver runs BEFORE project_initializer.
Also changed project_initializer mode from FORCE to AUTO to preserve existing content.

This ensures custom CLAUDE.md content ends up in PROJECT.md, not PROJECT.md.bak.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: rysweet

CLAUDE.md

@@ -1,3 +1,5 @@
+<!-- amplihack-version: 0.9.0 -->
+
 # CLAUDE.md
 
 This file provides guidance to Claude Code when working with your codebase. It
@@ -688,7 +690,9 @@ skill is:
 Amplihack includes production-ready scenario tools that follow the **Progressive
 Maturity Model**:
 
-**Note**: When users request "a tool", they typically mean an executable program (scenarios/), not a Claude Code skill (skills/). Build the tool first; optionally add a skill that calls it.
+**Note**: When users request "a tool", they typically mean an executable program
+(scenarios/), not a Claude Code skill (skills/). Build the tool first;
+optionally add a skill that calls it.
 
 ### Using Scenario Tools