#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/auth/src/health.ts

@@ -0,0 +1,26 @@
+import type { IncomingMessage, ServerResponse } from "node:http";
+
+type PingFn = () => Promise<void>;
+
+/**
+ * Builds the /health/live and /health/ready handler shared by the auth and
+ * storage services (PLAN.md section 11.5 and the compose healthcheck in section 13).
+ */
+export function buildHealthHandler(pingDb: PingFn, pingRedis: PingFn) {
+  return async (req: IncomingMessage, res: ServerResponse) => {
+    if (req.url === "/health/live") {
+      res.writeHead(200).end();
+      return;
+    }
+    if (req.url === "/health/ready") {
+      try {
+        await Promise.all([pingDb(), pingRedis()]);
+        res.writeHead(200).end();
+      } catch {
+        res.writeHead(503).end();
+      }
+      return;
+    }
+    res.writeHead(404).end();
+  };
+}