#1: implement F0 foundation - monorepo, migrations, Go domain layer, service skeletons, CI

Stands up the LambdaMail monorepo per PLAN.md's F0 milestone: local dev
scaffolding (.env.example, Makefile, .gitignore excluding PLAN.md/docs/
.superpowers/), the full initial Postgres schema as a golang-migrate
migration, the complete Go domain layer for services/protocols (value
objects, entities, domain events - zero external imports beyond
github.com/google/uuid) with unit tests, health-checked service skeletons
for auth/storage (TypeScript) and webmail (Next.js), a local
docker-compose.yaml wiring all services together, a language-enforcement
lint script, and a GitHub Actions CI workflow.

Built via 11 sequential tasks under subagent-driven development, each with
an independent implementer + reviewer cycle. Fixes applied during review:
DomainName.IsPunycode() added to satisfy the promised interface; ioredis
default-import typing under NodeNext; next.js bumped 15.0.3->15.5.21 to
resolve high/critical CVEs; lang-lint.mjs corrected to not flag its own
banned-terms list; web service healthcheck added so compose --wait
actually waits on it; webmail Dockerfile's missing public/ directory:
protocols go.mod version aligned with CI's Go 1.22 pin.

Known follow-ups for later phases (not blocking F0): go-arch-lint isn't
wired into CI yet; live docker compose up and migration apply have not
been exercised in this dev environment (no Docker/psql available here)
and will get their first real run in CI, which does have Docker.

services/protocols/internal/health/health_test.go

@@ -0,0 +1,38 @@
+package health
+
+import (
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestHandler_Live_AlwaysReturns200(t *testing.T) {
+	h := Handler(func() error { return errors.New("db down") })
+	req := httptest.NewRequest(http.MethodGet, "/health/live", nil)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Errorf("GET /health/live status = %d, want %d", rec.Code, http.StatusOK)
+	}
+}
+
+func TestHandler_Ready_Returns200WhenPingSucceeds(t *testing.T) {
+	h := Handler(func() error { return nil })
+	req := httptest.NewRequest(http.MethodGet, "/health/ready", nil)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Errorf("GET /health/ready status = %d, want %d", rec.Code, http.StatusOK)
+	}
+}
+
+func TestHandler_Ready_Returns503WhenPingFails(t *testing.T) {
+	h := Handler(func() error { return errors.New("db down") })
+	req := httptest.NewRequest(http.MethodGet, "/health/ready", nil)
+	rec := httptest.NewRecorder()
+	h.ServeHTTP(rec, req)
+	if rec.Code != http.StatusServiceUnavailable {
+		t.Errorf("GET /health/ready status = %d, want %d", rec.Code, http.StatusServiceUnavailable)
+	}
+}