refactor: delete stale files and consolidate .mindmodel structure

Deleted stale root-level Python files:
- main.py (unused 'Hello world' script)
- verify.py (unused table info script)
- scraper.py (unused MotionScraper class)
- scheduler.py (unused DataUpdateScheduler class)

Deleted duplicate .mindmodel root YAML files (subdirectory versions are more comprehensive):
- anti-patterns.yaml, architecture.yaml, conventions.yaml
- dependencies.yaml, domain.yaml, domain-glossary.yaml
- stack.yaml, tech-stack.yaml, workflows.yaml

Added comprehensive .mindmodel subdirectories:
- constraints/ (naming, db-schema, error-handling, types, etc.)
- patterns/ (api, architecture, database, python, streamlit, etc.)
- examples/ (code examples for each pattern)
- anti-patterns/, architecture/, conventions/, dependencies/, domain/, stack/

Updated ARCHITECTURE.md to reflect current codebase:
- Removed references to non-existent files
- Added missing files (explorer.py, explorer_helpers.py, pipeline/)
- Added directory structure documentation
- Updated tech stack to include scipy, sklearn, umap

Updated .gitignore:
- Added patterns for generated analysis files
- Added .worktrees/ pattern (was already in gitignore but dir was deleted)

Removed empty .worktrees/ directory

.mindmodel/architecture/architecture.yaml

@@ -0,0 +1,55 @@
+# Architecture
+
+## Page Routing
+- `Home.py` → thin wrapper, minimal logic
+- `pages/1_🗳️_Stemwijzer.py` → thin wrapper delegating to quiz module
+- `pages/2_🔍_Explorer.py` → thin wrapper delegating to `explorer.py`
+- **Pattern**: thin Streamlit page files that import and call into core modules
+
+## Core Modules
+```
+database.py          → MotionDatabase singleton (shared across all pages)
+explorer.py          → Explorer page logic, tab routing
+explorer_helpers.py  → Pure functions, chart builders, coordinate computation
+analysis/            → SVD, UMAP, clustering algorithms
+pipeline/            → Data ingestion pipeline
+config.py            → Dataclass Config, PARTY_COLOURS dict
+```
+
+## Data Flow
+```
+DuckDB → MotionDatabase (singleton)
+              ↓
+        st.cache_data loaders
+              ↓
+        explorer_helpers (pure functions)
+              ↓
+        Plotly charts → Streamlit
+```
+
+## Key Patterns
+1. **Singleton per module**: `database.py` exports one `db` instance; `config.py` exports config + PARTY_COLOURS
+2. **Graceful degradation**: try/except around optional dependencies (UMAP, Plotly)
+3. **Pipeline**: fetch → transform → store (see `pipeline/` directory)
+4. **API client**: with retry/backoff for external data sources
+5. **Dummy fallbacks**: if optional dep unavailable, use dummy stub
+
+## Database Schema (key relationships)
+```
+motions (id, title, date, category)
+  ↓
+mp_votes (mp_id, motion_id, vote: -1/0/1)
+  ↓
+svd_vectors (entity_id, window, vector_2d)  ← entity_id = mp_name OR party_name
+  ↓
+party_centroids (party, window, centroid_2d)
+  ↓
+mp_party_history (mp_id, party, start_date, end_date)
+```
+
+## SVD Computation Pipeline
+1. Build MP × Motion vote matrix from `mp_votes`
+2. Run SVD to get 2D embeddings per MP
+3. Optionally aggregate to party centroids
+4. Align across windows using Procrustes
+5. Store in `svd_vectors` table