feat(pipeline): implement parliamentary embedding pipeline MVP

- Add 4 migration files: mp_votes, mp_metadata, svd_vectors, fused_embeddings
- Extend database.py with 5 new helper methods and table init
- Add pipeline/ package: extract_mp_votes, fetch_mp_metadata, text_pipeline,
  svd_pipeline (with Procrustes alignment), fusion
- Add full test suite (17 tests) covering all pipeline modules and migrations
- Fix Procrustes alignment bug: scipy scale is a norm value, not a multiplier
- Fix DuckDB date type handling in test assertions (datetime.date vs string)
- Remove duckdb.py shim; tests now run against real duckdb + scipy via uv

Ref: thoughts/shared/plans/2026-03-21-parliamentary-embedding-pipeline-plan.md

thoughts/ledgers/CONTINUITY_stemwijzer.md

@@ -0,0 +1,50 @@
+# Session: stemwijzer
+Updated: 2026-03-20T00:23:33Z
+
+## Goal
+Preserve the minimal session state required to resume work on the stemwijzer project after context clears (success = ledger exists and is kept up-to-date).
+
+## Constraints
+- Keep the ledger CONCISE — only essential information
+- Focus on WHAT and WHY, not HOW
+- Mark uncertain information as UNCONFIRMED
+- Include git branch and key file paths
+
+## Progress
+### Done
+- [x] Create initial continuity ledger file
+
+### In Progress
+- [ ] Capture ongoing session context and update ledger after each meaningful change
+
+### Blocked
+- None currently
+
+## Key Decisions
+- **Session name = "stemwijzer"**: Chosen from repository context (UNCONFIRMED if a different canonical session name is preferred).
+- **Do not auto-commit ledger changes**: Commits will only be made when the user explicitly requests it (follows Git Safety Protocol).
+
+## Next Steps
+1. Continue updating this ledger when tasks, files, or decisions change
+2. Add entries for new branches or major feature work (mark as UNCONFIRMED when unsure)
+3. Ask user before creating any git commits that include this ledger
+
+## File Operations
+### Read
+- `README.md`
+- `pyproject.toml`
+- `thoughts/shared/plans/2026-03-19-stemwijzer-plan.md`
+- `thoughts/shared/designs/2026-03-19-stemwijzer-design.md`
+
+### Modified
+- `thoughts/ledgers/CONTINUITY_stemwijzer.md` (new)
+
+## Critical Context
+- Repository branch observed: `main`
+- Found project metadata in `pyproject.toml` indicating Python tooling preference
+- Existing notes/plans located under `thoughts/shared/` (plans and designs from 2026-03-19)
+- No existing continuity ledger was found prior to this creation
+
+## Working Set
+- Branch: `main`
+- Key files: `README.md`, `pyproject.toml`, `thoughts/shared/plans/2026-03-19-stemwijzer-plan.md`, `thoughts/shared/designs/2026-03-19-stemwijzer-design.md`, `thoughts/ledgers/CONTINUITY_stemwijzer.md`