Extract place_id

[xavier-villelegier]

Fixes #186

Summary

• Adds extraction of Google's place_id field from scraped place data

Changes

• Added PlaceID field to the Entry struct with JSON tag place_id
• Extract the value from darray[78] in EntryFromJSON()
• Added place_id column to CSV output
• Updated test fixture with expected place_id value

Why

The place_id is Google's stable unique identifier for a place (e.g., ChIJDdnwdv0y5xQRRytw1ihZQeU). Unlike cid or data_id, the place_id is:

• Used directly in Google Maps APIs (Places API, Geocoding API)
• Stable across Google Maps URL formats

This way, we can combine both API and scraper usage

Test plan

• go build ./... passes
• go test ./... passes