Fase 1a: microservicio tcef-notifications (workers FCM v1 + email)

Sustituye el envío de push por la API legacy de GCM (muerta desde jun-2024) y
saca el envío del observer de Meteor a una cola BullMQ controlada.

- poller: consume 'notifications' pendientes (campos correctos; el cron viejo
  tenía un typo nofitied/emailNofitied que nunca casaba)
- fcm-worker: firebase-admin (FCM HTTP v1), payload compatible con la app
  Flutter (FLUTTER_NOTIFICATION_CLICK, collapseKey=_id, data); purga tokens
  muertos sin reintentar
- email-worker: nodemailer + plantillas new-fire portadas verbatim
- idempotencia persistente: notification_sends, indice unico (notificationId,
  channel) -> sobrevive reinicios y replays
- salvaguardas anti-spam: modos dry-run/shadow/canary/full, exclusion mutua por
  canal (OWNED_CHANNELS + notifDisabledChannels en Meteor), kill switch,
  limites por usuario/dia y circuit breaker por batch
- docs/legacy-behavior.md (caracterizacion) + docs/rollout.md
- 47 tests (vitest + mongodb-memory-server), typecheck y build OK
- deploy: systemd + pm2 (Node 22 standalone)

Falta el service account de Firebase para envio real de push (pedir al usuario).

package.json

@@ -0,0 +1,38 @@
+{
+  "name": "tcef-notifications",
+  "version": "0.1.0",
+  "private": true,
+  "description": "Notification sending microservice for Todos contra el Fuego (FCM v1 + email, later Telegram). Replaces the dead node-gcm push path and the Meteor observer.",
+  "type": "module",
+  "engines": {
+    "node": ">=22"
+  },
+  "scripts": {
+    "build": "tsc -p tsconfig.json && node scripts/copy-templates.mjs",
+    "typecheck": "tsc -p tsconfig.json --noEmit",
+    "start": "node --enable-source-maps dist/index.js",
+    "dev": "node --experimental-strip-types --watch src/index.ts",
+    "test": "vitest run",
+    "test:watch": "vitest"
+  },
+  "dependencies": {
+    "bullmq": "^5.34.0",
+    "firebase-admin": "^13.0.2",
+    "handlebars": "^4.7.8",
+    "ioredis": "^5.4.2",
+    "juice": "^11.0.0",
+    "luxon": "^3.5.0",
+    "mongodb": "^6.12.0",
+    "nodemailer": "^6.9.16",
+    "pino": "^9.5.0",
+    "pino-pretty": "^13.0.0"
+  },
+  "devDependencies": {
+    "@types/luxon": "^3.4.2",
+    "@types/node": "^22.10.2",
+    "@types/nodemailer": "^6.4.17",
+    "mongodb-memory-server": "^11.2.0",
+    "typescript": "^5.7.2",
+    "vitest": "^2.1.8"
+  }
+}