#418 chore: simplify project-structure-validator agent

Summary

• Remove custom bash tooling (build-component-graph.sh and .gitignore)
• Replace with simpler tree-based approach that works across projects
• Agent now uses tree command instead of custom graph building script

Test plan

• Agent instructions only, no functional code changes

🤖 Generated with Claude Code

Summary by CodeRabbit

• Chores
  • Enhanced internal project structure validation tooling with improved workflow documentation and structural rules.
  • Removed legacy dependency analysis script.

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