Add OSM network generation tool

[jayzou3773]

Summary

Adds an OpenStreetMap network generation tool for LPSim. The tool converts live OSM data or an offline GraphML file into the current LPSim nodes.csv and edges.csv schemas.

Closes #106

Changes

• Add place-based and bounding-box OSM downloads
• Add offline GraphML input for reproducible workflows
• Filter unusable edges and select a configurable connected component
• Normalize speed units, lane counts, and parallel directed edges
• Generate deterministic dense node indices and edge IDs
• Preserve 64-bit OSM identifiers
• Add the lpsim-network command and usage documentation
• Add six offline acceptance tests

Usage

pip install -e '.[network]'

lpsim-network \
  --place "Berkeley, California, USA" \
  --output data/berkeley

The command produces:

data/berkeley/nodes.csv
data/berkeley/edges.csv

Testing

python -m pytest -q tests/test_generate_network.py
......                                                                   [100%]
6 passed in 1.11s

Additional checks:

• Ruff passed
• Black check passed
• Python byte-compilation passed
• Wheel build and console entry-point inspection passed

The automated tests cover:

• CLI input modes
• Exact output schemas
• Dense node and edge identifiers
• 64-bit OSM identifiers
• Connected-component selection
• Parallel-edge normalization
• Speed and lane normalization
• Deterministic byte-for-byte output
• Demand-generation compatibility
• Spatial-partition compatibility

Live OSM validation

A live bounding-box download generated:

• 55 nodes
• 125 directed edges
• 100 valid demand trips
• 2 valid spatial partitions containing all 55 nodes

Compatibility

• Existing LPSim behavior and CSV loading are unchanged
• No CI workflow changes are included
• Live OSM generation requires Python 3.9+ and the optional network dependencies
• Offline automated tests do not require network access

Limitations

• Live downloads depend on OSM Overpass availability
• Turn restrictions and traffic signals are not exported as separate simulation attributes