phase-0: foundation, both apps boot end to end

Monorepo (pnpm workspaces) with two deployable apps and three pure packages.

apps/api (Hono on Node): Zod validated env that fails fast and names the problem,
Kysely factories for SQLite and Postgres chosen by DATABASE_URL scheme, portable
migrations covering the whole SPEC section 5 schema, Better Auth with the four
roles and seeded demo accounts, localized error envelope, /healthz and /readyz,
graceful SIGTERM drain. Dialect specific SQL is confined to the two factories.

apps/web (Next.js App Router): locale routed shell in es and en with a language
switcher, sign in screen, and a runtime /api proxy so the browser only ever sees
one origin and cookies stay first party.

packages/i18n ships both catalogs complete; es is generated from COPY.md and a
test re-derives it from the document on every run so it cannot drift.
packages/contracts holds the Zod schemas and the typed client the web app uses.

Verified: 43 vitest tests, 14 Playwright tests on mobile and desktop, typecheck
and lint clean, migrate and seed from a clean database, sign in through the proxy
with CSRF rejection of foreign origins.

Not verified here: docker compose. This user has no access to the docker socket.

RULES.md is absent from docs/, so packages/rules exports only RULES_VERSION and
no tax rule, check digit or deadline was invented. See DECISIONS.md.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

apps/api/src/http/context.ts

@@ -0,0 +1,25 @@
+import type { Locale } from '@impuestos/i18n';
+import type { Auth } from '../auth/options';
+import type { DbHandle } from '../db/index';
+import type { Env } from '../lib/env';
+
+export interface SessionUser {
+  id: string;
+  email: string;
+  role: string;
+}
+
+export interface AppDeps {
+  env: Env;
+  handle: DbHandle;
+  auth: Auth;
+}
+
+/** Hono context typing shared by every route and middleware. */
+export interface AppEnv {
+  Variables: {
+    locale: Locale;
+    user: SessionUser | null;
+    deps: AppDeps;
+  };
+}