docs: restructure README with enhanced styling and organization

  - Add banner image at top of README as primary visual element
  - Reorganize demo assets with versioning (demo.legacy.v1.gif, demo.legacy.v2.gif)
  - Add early development notice as blockquote after demo
  - Simplify supported AI engines table to two-column format with hyperlinks
  - Replace emojis with ANSI symbols (✓, ⊙) for cleaner professional look
  - Fix table centering for Supported AI Engines and References sections
  - Add styled References section with links to docs, spec schema, and case study
  - Move detailed contributor info to CONTRIBUTORS.md
  - Centralize and streamline Contributors section with contribution call-to-action
  - Add package manager alternatives (bun/pnpm/yarn) to installation instructions
  - Add 'cm' shortcut alias to run command
  - Improve overall visual consistency and navigation throughout README

Author: moazbuilds

README.md

@@ -10,6 +10,8 @@
 <p align="center">
   <strong>CodeMachine</strong> is a CLI-native Orchestration Engine that runs coordinated multi-agent workflows directly on your local machine. It provides the runtime infrastructure to execute complex multi-agent topologies within your own environment. Designed to drive any high-level autonomous objective, it features a battle-tested Spec-to-Code blueprint—transforming your terminal into a factory for production-ready software. ⚡️<br></p>
 
+> **⚠️ Early Development Notice:** This project is in early development and is not yet ready for production use. Features may change, break, or be incomplete.
+
 <p align="center">
   <img src="docs/assets/demo.gif" alt="CodeMachine in Action" width="800">
 </p>
@@ -24,7 +26,6 @@
   This isn't a demo—it's proof. CodeMachine engine orchestrated its own architecture, planning, implementation, and testing—creating a massively scalable codebase ready for continuous updates and improvements.
 </p>
 
-
 ---
 
 ## Why CodeMachine?
@@ -39,14 +40,14 @@
 
 ### **Installing and running CodeMachine CLI**
 
-First, install the command-line tool globally via npm:
+First, install the command-line tool globally:
 ```bash
-npm install -g codemachine
+npm install -g codemachine   # or bun/pnpm/yarn
 ```
 
-Then, simply run `codemachine` in your project directory to get started.
+Then, simply run `codemachine` in your project directory to get started:
 ```bash
-codemachine
+codemachine   # or cm
 ```
 
 ### **Initializing a Project**
@@ -63,7 +64,7 @@ codemachine
 CodeMachine requires at least one CLI-based AI engine to handle the primary roles of planning and writing code, and is designed to orchestrate multiple engines to collaborate within a single workflow.
 
 <p align="center">
-<table>
+<table align="center">
   <thead>
     <tr>
       <th align="left">CLI Engine</th>
@@ -195,7 +196,7 @@ Found a bug or have a feature idea? Check our <strong><a href="./CONTRIBUTING.md
 ## 📖 References
 
 <p align="center">
-<table>
+<table align="center">
   <tbody>
     <tr>
       <td align="center" width="33%">