Implement PostgreSQL production store path

Add the PostgreSQL backend, migration and stopped-write transfer tools, lease-aware deployment manifests, tenancy declarations, and shared conformance coverage. Persist grouping mutations in durable stores and separate process liveness from database readiness.

migrations/postgres/0001_tenant_store.sql

@@ -0,0 +1,82 @@
+BEGIN;
+
+CREATE TABLE IF NOT EXISTS tenants (
+  tenant_id TEXT PRIMARY KEY,
+  identifier TEXT UNIQUE NOT NULL,
+  grouping_name TEXT NOT NULL,
+  display_name TEXT,
+  contact_email TEXT,
+  lifecycle TEXT NOT NULL DEFAULT 'active'
+    CHECK (lifecycle IN ('active', 'retired')),
+  version BIGINT NOT NULL DEFAULT 1 CHECK (version > 0),
+  -- Pre-lifecycle SQLite rows legitimately carry no timestamp. Nullable here
+  -- preserves them exactly during the store move; new domain writes set both.
+  created_at TIMESTAMPTZ,
+  updated_at TIMESTAMPTZ,
+  retired_at TIMESTAMPTZ,
+  reactivated_at TIMESTAMPTZ
+);
+
+CREATE TABLE IF NOT EXISTS grants (
+  grant_id TEXT PRIMARY KEY,
+  tenant_id TEXT NOT NULL REFERENCES tenants(tenant_id),
+  role TEXT NOT NULL,
+  grant_reason TEXT NOT NULL,
+  plan_id TEXT,
+  granted_by TEXT NOT NULL,
+  granted_at TIMESTAMPTZ NOT NULL,
+  correlation_id TEXT NOT NULL,
+  revoked_at TIMESTAMPTZ
+);
+CREATE INDEX IF NOT EXISTS grants_tenant_active_idx
+  ON grants (tenant_id) WHERE revoked_at IS NULL;
+
+CREATE TABLE IF NOT EXISTS plans (
+  tenant_id TEXT PRIMARY KEY REFERENCES tenants(tenant_id),
+  plan_id TEXT NOT NULL,
+  assigned_at TIMESTAMPTZ NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS events (
+  seq BIGINT GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
+  event_type TEXT NOT NULL,
+  tenant_id TEXT NOT NULL REFERENCES tenants(tenant_id),
+  at TIMESTAMPTZ NOT NULL,
+  payload JSONB NOT NULL
+);
+CREATE INDEX IF NOT EXISTS events_tenant_seq_idx ON events (tenant_id, seq);
+
+CREATE TABLE IF NOT EXISTS idempotency_receipts (
+  tenant_id TEXT NOT NULL REFERENCES tenants(tenant_id),
+  idempotency_key TEXT NOT NULL,
+  request_fingerprint TEXT NOT NULL,
+  result JSONB NOT NULL,
+  recorded_at TIMESTAMPTZ NOT NULL,
+  PRIMARY KEY (tenant_id, idempotency_key)
+);
+
+CREATE TABLE IF NOT EXISTS guardrail_overrides (
+  tenant_id TEXT NOT NULL REFERENCES tenants(tenant_id),
+  limit_key TEXT NOT NULL,
+  kind TEXT NOT NULL,
+  amount TEXT NOT NULL,
+  currency TEXT,
+  period TEXT,
+  PRIMARY KEY (tenant_id, limit_key)
+);
+
+CREATE TABLE IF NOT EXISTS guardrail_changes (
+  change_id TEXT PRIMARY KEY,
+  tenant_id TEXT NOT NULL REFERENCES tenants(tenant_id),
+  limit_key TEXT NOT NULL,
+  previous JSONB,
+  current JSONB,
+  changed_by TEXT NOT NULL,
+  reason TEXT NOT NULL,
+  correlation_id TEXT NOT NULL,
+  changed_at TIMESTAMPTZ NOT NULL
+);
+CREATE INDEX IF NOT EXISTS guardrail_changes_tenant_time_idx
+  ON guardrail_changes (tenant_id, changed_at, change_id);
+
+COMMIT;