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>

package.json

@@ -0,0 +1,34 @@
+{
+  "name": "impuestos",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "packageManager": "pnpm@10.32.1",
+  "engines": {
+    "node": ">=22"
+  },
+  "scripts": {
+    "dev": "pnpm -r --parallel dev",
+    "build": "pnpm -r build",
+    "typecheck": "pnpm -r typecheck",
+    "lint": "eslint .",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:e2e": "playwright test",
+    "db:migrate": "pnpm --filter @impuestos/api db:migrate",
+    "db:seed": "pnpm --filter @impuestos/api db:seed"
+  },
+  "devDependencies": {
+    "@eslint/js": "^10.0.1",
+    "@playwright/test": "^1.62.1",
+    "@types/node": "^26.4.1",
+    "eslint": "^10.9.1",
+    "eslint-plugin-react": "^7.37.5",
+    "eslint-plugin-react-hooks": "^7.1.1",
+    "globals": "^17.12.0",
+    "typescript": "^5.9.3",
+    "typescript-eslint": "^8.69.0",
+    "vitest": "^5.0.0",
+    "@impuestos/i18n": "workspace:*"
+  }
+}