refactor: CLI cleanup and documentation updates

- Refactor CLI metric computation to eliminate code duplication
- Update version format to PEP 440 compliance (0.1.0.dev0)
- Cache Settings instance via @lru_cache for performance
- Document composite validators' protocol deviation
- Consolidate redundant empty checks in ROUGE-L computation
- Add Phase 10 (Portfolio Demos) to implementation plan

docs/implementation-plan.md

@@ -871,6 +871,59 @@ uv run pytest --cov=src/veritext --cov-report=term-missing
 
 ---
 
+### Phase 10: Portfolio Demos
+
+**Goal:** Interactive demos for showcasing Veritext without installation.
+
+**Step 1 — Streamlit Demo:**
+
+Build a quick interactive web UI for general visitors.
+
+- [ ] Create `demo/streamlit_app.py`
+- [ ] Text input boxes (candidate + reference)
+- [ ] Metric selector (BLEU, ROUGE, lexical, readability)
+- [ ] Threshold sliders for pass/fail validation
+- [ ] Results table with scores and status
+- [ ] Deploy to homeserver (e.g., `veritext.kschappell.com`)
+
+**Step 2 — Jupyter Notebook Collection:**
+
+Deep-dive notebooks targeting data science and ML recruiters.
+
+- [ ] Create `notebooks/` directory
+- [ ] `01-metrics-overview.ipynb` — Introduction to each metric with visualisations
+- [ ] `02-batch-evaluation.ipynb` — Evaluating model outputs at scale
+- [ ] `03-regression-detection.ipynb` — Tracking quality over time
+- [ ] `04-chatbot-validation.ipynb` — Real-world use case
+
+**Step 3 — JupyterLite Deployment:**
+
+Host notebooks as static files running in the browser.
+
+- [ ] Configure JupyterLite build with veritext pre-installed
+- [ ] Bundle notebooks into static site
+- [ ] Deploy alongside Streamlit demo
+
+**Files:**
+- `demo/streamlit_app.py`
+- `notebooks/01-metrics-overview.ipynb`
+- `notebooks/02-batch-evaluation.ipynb`
+- `notebooks/03-regression-detection.ipynb`
+- `notebooks/04-chatbot-validation.ipynb`
+- `notebooks/jupyterlite-config.json`
+
+**Verification:**
+```bash
+# Streamlit
+uv run streamlit run demo/streamlit_app.py
+
+# JupyterLite (local preview)
+jupyter lite build --contents notebooks/
+jupyter lite serve
+```
+
+---
+
 ## Dependencies
 
 ```toml