feat: Simple nodemailer integration

roadmap.md

@@ -0,0 +1,104 @@
+```
+
+``` md
+  ## Immediate
+
+  User registers: AuthService saves the user and emits a UserSignedUpEvent.
+
+  Listener catches it: The WelcomeEmailListener hears the event.
+
+  Queue handles it: The listener adds a job to BullMQ called send-welcome-email.
+
+  Worker processes it: A separate background worker picks up the job, tries to send the email, and automatically handles retries if it fails.
+```
+```
+
+
+# 🏗️ SaaS Architect’s Roadmap: NestJS & DevOps
+
+This document serves as a strategic guide for evolving from a developer to an architect. It balances the "What" (the technology) with the "How" (the engineering mindset).
+
+---
+
+## 🛠️ Phase 1: The "What" — Advanced Backend Features
+*Focus: Scaling complexity and ensuring production-grade reliability.*
+
+### 1. Advanced Multi-Tenancy Architecture
+* **The Goal:** Move beyond simple `organization_id` filters to true data isolation.
+* **Concepts:** Shared Database/Separate Schema or **Row Level Security (RLS)**.
+* **Challenge:** Implement a NestJS `Interceptor` or `Provider` that extracts a `tenant_id` from the request and automatically switches the database context/schema.
+
+
+### 2. Background Tasks & Reliability
+* **The Goal:** Decouple time-consuming tasks from the request/response cycle.
+* **Tech Stack:** **BullMQ** + **Redis**.
+* **Implementation:** Offload email invitations, image processing, and report generation to a separate "Worker" instance.
+
+
+### 3. Real-Time Interactions
+* **The Goal:** Create a reactive, living dashboard.
+* **Tech Stack:** **Socket.io** (WebSockets).
+* **Implementation:** Sync team membership changes or notification counts in real-time without requiring a page refresh.
+
+### 4. Billing & Webhooks (The SaaS "S")
+* **The Goal:** Turn a project into a business.
+* **Tech Stack:** **Stripe API**.
+* **Learning Point:** Handle **Idempotency**. Ensure that if Stripe sends a "Payment Success" webhook twice, you only upgrade the user's account once.
+
+---
+
+## 🧠 Phase 2: The "How" — Architectural Thinking
+*Focus: Designing systems that don't break under edge cases.*
+
+### 1. State Machine Logic
+Stop thinking in "CRUD" (Create, Read, Update, Delete) and start thinking in **Transitions**.
+* **Entity Lifecycle:** An Invitation isn't just a row; it's a flow: `Pending` → `Accepted` | `Declined` | `Expired`.
+* **Action:** Explicitly define what happens during every status change (e.g., "On Accept: Create User, Join Team, Clear Invite Cache").
+
+
+### 2. Atomic Transactions
+Never perform "partial" updates.
+* **Strategy:** Use Database Transactions (`BEGIN...COMMIT`) for any operation touching multiple tables. If the user joins the team but the invitation update fails, the whole thing must roll back.
+
+### 3. Event-Driven Side Effects
+Don't bloat your services with 10 different tasks.
+* **Pattern:** Use an **Event Emitter**.
+* **Logic:** `UserService.create()` emits a `USER_CREATED` event. Separate listeners then handle the email, the analytics ping, and the Slack notification independently.
+
+---
+
+## ☁️ Phase 3: The DevOps Pillar
+*Focus: Automation, Observability, and "Infrastructure as Code".*
+
+### 1. Observability (Stop Guessing)
+* **Structured Logging:** Use **Pino** to output JSON logs that include `trace_id` and `tenant_id`.
+* **Tracing:** Implement **OpenTelemetry** to visualize the lifecycle of a request across different services.
+
+
+### 2. Infrastructure as Code (IaC)
+* **The Goal:** Destroy and rebuild your entire cloud environment in minutes.
+* **Tech Stack:** **Terraform**.
+* **Action:** Codify your GCP/Azure VMs, VPC Firewalls, and Managed Databases so you never have to click buttons in a portal manually.
+
+### 3. Hardened CI/CD
+* **The Goal:** Catch errors before they hit production.
+* **Action:** Add "Structure Verification" steps in your GitHub Actions to ensure the build folder matches what the server expects (e.g., checking for Next.js standalone chunks).
+
+---
+
+## 🤖 The "Anti-GIGO" AI Workflow
+*How to use AI as an architect, not a typist.*
+
+1.  **Sketch First:** Define your DB schema and logic flow on a whiteboard before opening the chat.
+2.  **Hunt Edge Cases:** Ask yourself: "What if the user is already in another org? What if the database is locked?"
+3.  **Prompt as an Architect:**
+    * *Bad:* "Make an invite system."
+    * *Good:* "Design a NestJS service for an Invitation State Machine. It must use a database transaction, handle BullMQ for email side-effects, and include a unique constraint on (email, organization_id)."
+4.  **Audit the Output:** Check for N+1 query problems, lack of input validation, and missing error handling.
+
+---
+
+**Next Steps for You:**
+* Start with the **Invitation State Machine**.
+* Implement **BullMQ** for the invitation email.
+* Write your first **Terraform** script to manage your GCP firewall.