docs: add Overton analysis to README and AGENTS conventions

AGENTS.md

@@ -18,3 +18,7 @@
 
 - Right-wing parties (PVV, FVD, JA21, SGP) must appear on the RIGHT side of all axes in visualizations
 - SVD labels should reflect voting patterns, not semantic content — see `docs/solutions/best-practices/svd-labels-voting-patterns-not-semantics.md`
+- Centrist definition for Overton analysis: strict 4-party (D66, CDA, CU, NSC) — not VVD/BBB
+- Right-wing motion classification uses hybrid keywords + voting pattern approach — see `analysis/right_wing/classify_motions.py`
+- Two-dimensional extremity scoring separates stylistic (language) from material (policy impact) — see `.opencode/skills/score-extremity/SKILL.md`
+- SVD axis sign convention after Procrustes: axis 2 negative = nationalist (PVV -0.56), positive = kosmopolitisch (Volt +0.27) — see `docs/solutions/best-practices/overton-window-shift-methodology-2026-05-24.md`

README.md

@@ -14,6 +14,7 @@ Stemwijzer ingests motions and voting records from the Dutch House of Representa
 - **Explorer** — Interactive SVD visualizations, party trajectories over time, motion browser, and semantic search
 - **Analytics** — SVD decomposition of voting patterns, UMAP projections, clustering, and drift analysis
 - **LLM Enrichment** — Automatic generation of layman-friendly motion explanations using QWEN via OpenRouter
+- **Overton Window Analysis** — Quantitative analysis of whether the Dutch parliamentary center has shifted rightward, using centrist voting support, SVD spatial drift, 2D extremity scoring, and mechanism classification
 
 ## Prerequisites
 
@@ -62,6 +63,8 @@ The app will be available at http://localhost:8501.
 - **[ARCHITECTURE.md](ARCHITECTURE.md)** — Comprehensive architecture overview, tech stack, and contributor guidance
 - **[CODE_STYLE.md](CODE_STYLE.md)** — Coding conventions, naming, typing, and testing standards
 - **[docs/solutions/](docs/solutions/)** — Documented solutions to past bugs and best practices
+- **[Overton Window Analysis](reports/overton_window/overton_window_synthesis.md)** — Full analysis of whether the Dutch Overton window shifted right (2016–2026)
+- **[Overton Blog Post](reports/overton_window/blog_post.html)** — Public-facing summary with visualizations
 
 ## Tech Stack