test: add unit and integration test suites

- Extract evaluateCondition + rule types into src/lib/rules.ts for testability
- 48 unit tests for evaluateCondition (all fields/operators) and formatCategory
- 21 integration tests for getTransactions filters and getParticipantBalances
- Vitest configs for unit (vitest.config.ts) and integration (vitest.integration.config.ts)
- setup-test-db.sh creates personal_test DB from production schema via pg_dump
- Use vi.doMock + dynamic import pattern to isolate test DB from Prisma singleton

scripts/setup-test-db.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+# Creates the personal_test database and writes .env.test
+# Run once before integration tests: npm run test:setup
+
+set -e
+
+PG_CONTAINER=postgres-personal
+PG_USER=personal
+PG_PASS=personalpassword123
+TEST_DB=personal_test
+
+# Discover the container's bridge IP (accessible from the host on Linux)
+PG_HOST=$(docker inspect "$PG_CONTAINER" \
+  --format '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' 2>/dev/null | head -1)
+
+if [ -z "$PG_HOST" ]; then
+  echo "ERROR: Could not find container '$PG_CONTAINER'"
+  exit 1
+fi
+
+echo "Postgres container at $PG_HOST:5432"
+
+# Create test database (ignore error if it already exists)
+docker exec "$PG_CONTAINER" psql -U "$PG_USER" -d postgres \
+  -c "CREATE DATABASE $TEST_DB;" 2>/dev/null || true
+
+# Wipe and rebuild schema from production (schema only, no data)
+echo "Copying schema from $PG_USER to $TEST_DB..."
+docker exec "$PG_CONTAINER" pg_dump -U "$PG_USER" --schema-only "$PG_USER" \
+  | docker exec -i "$PG_CONTAINER" psql -U "$PG_USER" -d "$TEST_DB" -q
+
+echo "Schema ready."
+
+# Write .env.test
+cat > "$(dirname "$0")/../.env.test" << EOF
+DATABASE_URL=postgresql://$PG_USER:$PG_PASS@$PG_HOST:5432/$TEST_DB
+EOF
+
+echo ".env.test written — integration tests can now run with: npm run test:integration"