Add location-based theater search

[tducret]

Summary

• add the public Location model and Allocine.get_geocodes() for department and city discovery
• extend search_theaters() to search by geocode, department, or zipcode
• handle pagination, Allociné obfuscated links, Paris routing, and invalid location filters
• cover location discovery and theater searches with VCR cassettes and JSON snapshots

Tests

• uv run pytest
• uv run ruff check .
• uv run ruff format --check .
• uv run ty check