Implement Phase 0b base project against the frozen test contract

All seven services (gateway, ledger, fraud, sanctions, insights, notifier,
audit), db/schema.sql plus optional_indexes.sql, scripts/seed.py and
smoke.py, the gateway-served frontend, and docker-compose.yml. Plain-text
stdlib logging and a weak manual X-Request-Id only -- no observability yet,
by design, per test_no_observability.py. Implements all 13 named chaos-flag
pathologies from docs/PATHOLOGIES.md behind Redis-backed runtime flags.

make smoke and make test-contract pass; make test-baseline and
make test-pathology pass except for a handful of load-sensitive tests
documented in tests/README.md rather than papered over.

Makefile

@@ -0,0 +1,70 @@
+# Ledgerline -- application targets (phase-0-base-project-spec.md §12) plus
+# the Phase 0a test-suite targets. `make up && make seed` are prerequisites
+# for every test target below.
+
+PYTEST ?= pytest
+COMPOSE ?= docker compose
+SEED_DSN ?= postgresql://ledgerline:ledgerline@postgres:5432/ledgerline
+GATEWAY_URL ?= http://localhost:8000
+
+.PHONY: up down logs seed reset smoke \
+        chaos-clean chaos-light chaos-nightmare chaos-random \
+        fix-index drop-index \
+        test test-contract test-baseline test-pathology test-slow test-all
+
+up:
+	$(COMPOSE) up -d --build
+
+down:
+	$(COMPOSE) down
+
+logs:
+	$(COMPOSE) logs -f
+
+seed:
+	cat db/schema.sql | $(COMPOSE) exec -T postgres psql -U ledgerline -d ledgerline
+	$(COMPOSE) run --rm -e POSTGRES_DSN=$(SEED_DSN) gateway python scripts/seed.py
+
+reset:
+	$(COMPOSE) down -v
+	$(MAKE) up
+	$(MAKE) seed
+
+smoke:
+	$(COMPOSE) run --rm -e POSTGRES_DSN=$(SEED_DSN) -e GATEWAY_URL=http://gateway:8000 gateway python scripts/smoke.py
+
+chaos-clean:
+	curl -sf -X POST $(GATEWAY_URL)/api/admin/chaos/profile -H 'Content-Type: application/json' -d '{"profile":"clean"}'
+
+chaos-light:
+	curl -sf -X POST $(GATEWAY_URL)/api/admin/chaos/profile -H 'Content-Type: application/json' -d '{"profile":"light"}'
+
+chaos-nightmare:
+	curl -sf -X POST $(GATEWAY_URL)/api/admin/chaos/profile -H 'Content-Type: application/json' -d '{"profile":"nightmare"}'
+
+chaos-random:
+	curl -sf -X POST $(GATEWAY_URL)/api/admin/chaos/profile -H 'Content-Type: application/json' -d '{"profile":"random"}'
+
+fix-index:
+	cat db/optional_indexes.sql | $(COMPOSE) exec -T postgres psql -U ledgerline -d ledgerline
+
+drop-index:
+	cat db/drop_indexes.sql | $(COMPOSE) exec -T postgres psql -U ledgerline -d ledgerline
+
+test:
+	$(PYTEST) -m "not slow"
+
+test-contract:
+	$(PYTEST) -m "contract or seed or guard"
+
+test-baseline:
+	$(PYTEST) -m baseline
+
+test-pathology:
+	$(PYTEST) -m "pathology and not slow"
+
+test-slow:
+	$(PYTEST) -m slow
+
+test-all:
+	$(PYTEST)