Add 'Getting Started' tutorial with step-by-step wizard

[AmitoVrito]

Description

Create an interactive getting-started tutorial.

What to do

• Create docs/tutorial/ with sub-pages:
  1. Installation & setup
  2. Your first RAG pipeline
  3. Adding an agent with tools
  4. Building a graph workflow
  5. Deploying to production
• Each step has: explanation, code, expected output
• Add progress tracking (step 1 of 5)
• Add to sidebar as top-level 'Tutorial' section

[AmitoVrito]

Thanks for your interest! I will assign it to you. Before you start, could you give the repo a ⭐ on the main repo (https://github.com/SynapseKit/SynapseKit)? It really helps with visibility for a new project. Looking forward to your PR!