#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/cmd/lambdamail-protocols/main.go

@@ -0,0 +1,30 @@
+// Command lambdamail-protocols is the entry point for the protocols service.
+// F0 boots only the health endpoint; SMTP/IMAP/POP3/ManageSieve listeners land in F1/F2.
+package main
+
+import (
+	"database/sql"
+	"log"
+	"net/http"
+	"os"
+
+	_ "github.com/lib/pq"
+	"lambdamail/protocols/internal/health"
+)
+
+func main() {
+	dbURL := os.Getenv("DATABASE_URL")
+	db, err := sql.Open("postgres", dbURL)
+	if err != nil {
+		log.Fatalf("open database: %v", err)
+	}
+	defer db.Close()
+
+	handler := health.Handler(func() error { return db.Ping() })
+
+	addr := ":8080"
+	log.Printf("lambdamail-protocols listening on %s (health only - F0 scaffold)", addr)
+	if err := http.ListenAndServe(addr, handler); err != nil {
+		log.Fatalf("serve: %v", err)
+	}
+}