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

migrations/2026-03-19-add-embeddings.sql

@@ -0,0 +1,11 @@
+-- Add a separate embeddings table for semantic search and storage of vectors (DuckDB-compatible)
+CREATE TABLE IF NOT EXISTS embeddings (
+    id INTEGER,
+    motion_id INTEGER NOT NULL,
+    model TEXT NOT NULL,
+    vector JSON NOT NULL,
+    created_at TIMESTAMP DEFAULT current_timestamp
+);
+-- DuckDB does not support AUTOINCREMENT; emulate id via a sequence if needed elsewhere
+CREATE SEQUENCE IF NOT EXISTS embeddings_id_seq START 1;
+-- Populate id via trigger-like insert pattern is handled by application code (select nextval when inserting)

migrations/2026-03-20-add-body-text.sql

@@ -0,0 +1,6 @@
+-- Migration: add externe_identifier and body_text columns to motions
+-- externe_identifier: e.g. "kst-36600-VII-28" from DocumentVersie.ExterneIdentifier
+-- body_text: full plain-text motion body scraped from officielebekendmakingen.nl
+
+ALTER TABLE motions ADD COLUMN IF NOT EXISTS externe_identifier VARCHAR;
+ALTER TABLE motions ADD COLUMN IF NOT EXISTS body_text VARCHAR;

migrations/2026-03-22-add-audit-events.sql

@@ -0,0 +1,24 @@
+-- Migration: create audit_events table
+-- Date: 2026-03-22
+-- Description: Placeholder migration to add an audit_events table to record audit logs.
+--
+-- Decision: The actual SQL is intentionally left commented out to avoid making
+-- database changes during test runs. When ready to apply, uncomment and
+-- adapt the SQL for your database engine.
+
+/*
+CREATE TABLE audit_events (
+    id UUID PRIMARY KEY,
+    actor_id UUID NOT NULL,
+    action TEXT NOT NULL,
+    target_type TEXT,
+    target_id UUID,
+    metadata JSONB,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT now()
+);
+
+-- Add indexes as needed, e.g.:
+-- CREATE INDEX ON audit_events (actor_id);
+*/
+
+-- End of migration placeholder

migrations/2026-03-22-add-similarity-cache.sql

@@ -0,0 +1,15 @@
+-- 2026-03-22-add-similarity-cache.sql
+-- Placeholder migration for adding a similarity_cache table
+-- Decision: Keep SQL commented out so CI does not accidentally modify databases.
+
+/*
+-- Example (commented out):
+CREATE TABLE similarity_cache (
+    id SERIAL PRIMARY KEY,
+    key TEXT NOT NULL,
+    vector FLOAT8[] NOT NULL,
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT now()
+);
+*/
+
+-- No executable SQL in this file. Intentionally left as a safe no-op.

migrations/2026_03_21__create_fused_embeddings.sql

@@ -0,0 +1,13 @@
+----SQL
+CREATE SEQUENCE IF NOT EXISTS fused_embeddings_id_seq START 1;
+CREATE TABLE IF NOT EXISTS fused_embeddings (
+    id INTEGER DEFAULT nextval('fused_embeddings_id_seq'),
+    motion_id INTEGER NOT NULL,
+    window_id TEXT NOT NULL,
+    vector JSON NOT NULL,
+    svd_dims INTEGER NOT NULL,
+    text_dims INTEGER NOT NULL,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (id)
+);
+----END

migrations/2026_03_21__create_mp_metadata.sql

@@ -0,0 +1,9 @@
+----SQL
+CREATE TABLE IF NOT EXISTS mp_metadata (
+    mp_name TEXT PRIMARY KEY,
+    party TEXT,
+    van DATE,
+    tot_en_met DATE,
+    persoon_id TEXT
+);
+----END

migrations/2026_03_21__create_mp_votes.sql

@@ -0,0 +1,13 @@
+----SQL
+CREATE SEQUENCE IF NOT EXISTS mp_votes_id_seq START 1;
+CREATE TABLE IF NOT EXISTS mp_votes (
+    id INTEGER DEFAULT nextval('mp_votes_id_seq'),
+    motion_id INTEGER NOT NULL,
+    mp_name TEXT NOT NULL,
+    party TEXT,
+    vote TEXT NOT NULL,
+    date DATE,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (id)
+);
+----END

migrations/2026_03_21__create_svd_vectors.sql

@@ -0,0 +1,13 @@
+----SQL
+CREATE SEQUENCE IF NOT EXISTS svd_vectors_id_seq START 1;
+CREATE TABLE IF NOT EXISTS svd_vectors (
+    id INTEGER DEFAULT nextval('svd_vectors_id_seq'),
+    window_id TEXT NOT NULL,
+    entity_type TEXT NOT NULL,
+    entity_id TEXT NOT NULL,
+    vector JSON NOT NULL,
+    model TEXT,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    PRIMARY KEY (id)
+);
+----END