refactor: clean package structure with single-import SDKs

BREAKING CHANGE: Package paths have been reorganized for clarity

## Major Changes

### Package Structure
- Collapsed engine/core → engine (removed unnecessary nesting)
- Moved core/types → types (top-level types package)
- Added root facade for single-import experience
- Removed redundant factory.go

### SDK Improvements
All SDKs now provide single-import interfaces:
- Go: import "github.com/luxfi/consensus"
- Python: import lux_consensus as consensus
- Rust: use lux_consensus::*

### Documentation
- Added comprehensive introduction and architecture docs
- Created AI/ML integration guide for researchers
- Added research section with papers and experiments
- Improved sidebar organization and discoverability

### Benefits
- Shallow, obvious import paths
- One responsibility per package
- DRY, composable, orthogonal design
- Idiomatic patterns for each language
- Consistent API across all SDKs

This refactor provides a clean, intuitive developer experience where
one import is enough and things work one way only.

pkg/python/examples/simple_consensus.py

@@ -0,0 +1,168 @@
+#!/usr/bin/env python3
+"""
+Simple consensus example using the Lux Consensus Python SDK.
+
+Shows how to:
+- Create and start a consensus engine
+- Add blocks
+- Record votes
+- Check consensus status
+
+Copyright (C) 2019-2025, Lux Industries Inc. All rights reserved.
+"""
+
+import lux_consensus as consensus  # Single clean import!
+
+
+def main():
+    """Main example demonstrating consensus operations"""
+    
+    # Create engine with default config
+    config = consensus.default_config()
+    chain = consensus.new_chain(config)
+    
+    # Start the engine
+    chain.start()
+    
+    # Create a new block
+    block = consensus.Block(
+        id=consensus.ID(1, 2, 3),
+        parent_id=consensus.GENESIS_ID,
+        height=1,
+        payload=b"Hello, Lux Consensus from Python!"
+    )
+    
+    # Add the block
+    chain.add(block)
+    print(f"Added block {block.id} at height {block.height}")
+    
+    # Simulate votes from validators
+    validators = [consensus.ID(i) for i in range(1, 21)]
+    
+    # Vote on the block
+    for i, validator in enumerate(validators):
+        vote = consensus.new_vote(
+            block.id,
+            consensus.VOTE_PREFERENCE,
+            validator
+        )
+        vote.signature = f"sig-{i}".encode()
+        
+        chain.record_vote(vote)
+    
+    # Check if the block is accepted
+    if chain.is_accepted(block.id):
+        print("Block accepted! ✅")
+        print(f"Status: {chain.get_status(block.id).name}")
+    else:
+        print("Block not yet accepted")
+        print(f"Status: {chain.get_status(block.id).name}")
+    
+    # Create another block using helper
+    block2 = consensus.new_block(
+        consensus.ID(4, 5, 6),
+        block.id,
+        2,
+        b"Second block from Python"
+    )
+    
+    # Add and vote on the second block
+    chain.add(block2)
+    
+    # Vote with quorum
+    for i in range(config.alpha):
+        vote = consensus.new_vote(
+            block2.id,
+            consensus.VOTE_COMMIT,
+            validators[i]
+        )
+        vote.signature = f"sig2-{i}".encode()
+        
+        chain.record_vote(vote)
+    
+    # Both blocks should be accepted
+    print("\nConsensus Results:")
+    print(f"Block 1 accepted: {chain.is_accepted(block.id)}")
+    print(f"Block 2 accepted: {chain.is_accepted(block2.id)}")
+    
+    # Stop the engine
+    chain.stop()
+
+
+def quick_start_example():
+    """Example using the quick_start helper for even simpler initialization"""
+    
+    # One-liner to start consensus
+    chain = consensus.quick_start()
+    
+    # Ready to use!
+    block = consensus.new_block(
+        consensus.ID(1, 2, 3),
+        consensus.GENESIS_ID,
+        1,
+        b"Quick start block from Python"
+    )
+    
+    chain.add(block)
+    print("QuickStart example complete!")
+    
+    chain.stop()
+
+
+def advanced_example():
+    """Advanced example with custom configuration"""
+    
+    # Custom configuration
+    config = consensus.Config(
+        alpha=15,  # Lower quorum requirement
+        k=15,
+        max_outstanding=5,
+        network_timeout=10.0,
+        quantum_resistant=True,
+        gpu_acceleration=True
+    )
+    
+    chain = consensus.new_chain(config)
+    chain.start()
+    
+    # Create a chain of blocks
+    parent = consensus.GENESIS_ID
+    for i in range(5):
+        block = consensus.Block(
+            id=consensus.ID(i, i, i),
+            parent_id=parent,
+            height=i + 1,
+            payload=f"Block {i}".encode()
+        )
+        
+        chain.add(block)
+        
+        # Vote on the block
+        validators = [consensus.ID(v) for v in range(20)]
+        for v in validators[:config.alpha]:
+            vote = consensus.Vote(
+                block_id=block.id,
+                vote_type=consensus.VOTE_COMMIT,
+                voter=v
+            )
+            chain.record_vote(vote)
+        
+        if chain.is_accepted(block.id):
+            print(f"Block {i} accepted at height {block.height}")
+            parent = block.id
+    
+    print(f"\nFinal chain height: {chain.height}")
+    print(f"Last accepted block: {chain.last_accepted}")
+    
+    chain.stop()
+
+
+if __name__ == "__main__":
+    print("=== Simple Consensus Example ===")
+    main()
+    
+    print("\n=== QuickStart Example ===")
+    quick_start_example()
+    
+    print("\n=== Advanced Example ===")
+    advanced_example()