fix(skill): restructure tech-stack-evaluator with Progressive Disclosure (#64) (#120)

Restructure skill to follow Progressive Disclosure Architecture:

Structure Changes:
- Move Python scripts to scripts/ directory
- Move sample JSON files to assets/ directory
- Create references/ directory with extracted content
- Remove redundant HOW_TO_USE.md and README.md

New Reference Files:
- references/metrics.md: Detailed scoring algorithms and formulas
- references/examples.md: Concrete input/output examples
- references/workflows.md: Step-by-step evaluation workflows

SKILL.md Improvements:
- Reduced from 430 lines to ~180 lines
- Added table of contents
- Added trigger phrases in description
- Consistent imperative voice
- Points to references for details

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

engineering-team/tech-stack-evaluator/assets/sample_input_text.json

@@ -0,0 +1,4 @@
+{
+  "format": "text",
+  "input": "Compare React vs Vue for building a SaaS dashboard with real-time collaboration features. Our team has 8 developers, and we need to consider developer experience, ecosystem maturity, and performance."
+}