Mamba Architecture

# Mamba - Selective State Space Models

## Quick start

Mamba is a state-space model architecture achieving O(n) linear complexity for sequence modeling.

**Installation**:
```bash
# Install causal-conv1d (optional, for efficiency)
pip install causal-conv1d>=1.4.0

# Install Mamba
pip install mamba-ssm
# Or both together
pip install mamba-ssm[causal-conv1d]
```

**Prerequisites**: Linux, NVIDIA GPU, PyTorch 1.12+, CUDA 11.6+

**Basic usage** (Mamba block):
```python
import torch
from mamba_ssm import Mamba

batch, length, dim = 2, 64, 16
x = torch.randn(batch, length, dim).to("cuda")

model = Mamba(
    d_model=dim,      # Model dimension
    d_state=16,       # SSM state dimension
    d_conv=4,         # Conv1d kernel size
    expand=2          # Expansion factor
).to("cuda")

y = model(x)  # O(n) complexity!
assert y.shape == x.shape
```

## Common workflows

### Workflow 1: Language model with Mamba-2

**Complete LM with generation**:
```python
from mamba_ssm.models.mixer_seq_simple import MambaLMHeadModel
from mamba_ssm.models.config_mamba import MambaConfig
import torch

# Configure Mamba-2 LM
config = MambaConfig(