Update documentation and feasibility report with results

[William-Hill]

Summary

Update project documentation with actual training results, model selection rationale, and deployment instructions.

Depends On

• Train and evaluate Qwen 3.5-4B + Gemma 4 E4B on Colab #101 (trained + evaluated models)

Tasks

• Update docs/fine-tuning-feasibility-report.md:
  • Replace estimates with actual metrics (per-task, per-model-size)
  • Add model selection rationale (why 4B or 9B won)
  • Add actual training costs
  • Update recommended approach based on real results
• Update CLAUDE.md:
  • Add MODEL_BACKEND/OLLAMA_BASE_URL/MODEL_SIZE env var documentation
  • Add fine-tuned model info to Tech Stack table
  • Add training notebook to Key Entry Points
• Update README.md:
  • Add fine-tuned model section
  • Add Ollama setup instructions
• Update codebenders-dashboard/DASHBOARD_README.md:
  • Document MODEL_BACKEND config
  • Add SHAP narrator feature description

Acceptance Criteria

• Feasibility report reflects actual results, not estimates
• New developer can set up Ollama + fine-tuned models from README alone