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/tsup.config.ts

@@ -0,0 +1,17 @@
+import { defineConfig } from 'tsup';
+
+/**
+ * The workspace packages are pure TypeScript source with no build step, so they are
+ * bundled in here. Everything from node_modules stays external, which keeps the native
+ * better-sqlite3 binding loading normally at runtime.
+ */
+export default defineConfig({
+  entry: { index: 'src/index.ts', 'db/migrate.cli': 'src/db/migrate.cli.ts', 'db/seed.cli': 'src/db/seed.cli.ts' },
+  format: ['esm'],
+  target: 'node22',
+  platform: 'node',
+  outDir: 'dist',
+  clean: true,
+  sourcemap: true,
+  noExternal: [/^@impuestos\//],
+});