Update event_type enum values to snake_case

[chrisyamas]

Summary

In addition to being a normative change (that requires data migration for existing TIDES implementations) this is also a breaking change. This change updates passenger_events.event_type enum values from 'Sentence case' with spaces to snake_case for improved code compatibility.

Resolves #235

Changes

• spec/passenger_events.schema.json updated event_type enum from Sentence case to snake_case. Note: In addition to the snake_case conversion, this PR also removes unnecessary characters/words from several of the enum values for the sake of conciseness. I am eager from TIDES Contributors for input on those modifications. Here are all enum value changes:
  • Vehicle arrived at stop --> vehicle_arrived,
  • Vehicle departed stop --> vehicle_departed
  • Door opened --> door_opened
  • Door closed --> door_closed
  • Passenger boarded --> passenger_boarded
  • Passenger alighted --> passenger_alighted
  • Kneel was engaged --> kneel_engaged
  • Kneel was disengaged --> kneel_disengaged
  • Ramp was deployed --> ramp_deployed
  • Ramp was raised --> ramp_raised
  • Ramp deployment failed --> ramp_failed
  • Lift was deployed --> lift_deployed
  • Lift was raised --> lift_raised
  • Individual bike boarded --> bike_boarded
  • Individual bike alighted --> bike_alighted
  • Bike rack deployed --> bike_rack_deployed
• CHANGELOG.md added BREAKING change entry under [Unreleased] section

Reason for this change

The original 'Sentence case' enum values with spaces (e.g., "Vehicle arrived at stop") create unnecessary friction for some data manipulation operations in code. Values formatted in this way must be quoted in queries, cannot be used as variable names, and require case handling.

The new snake_case format (vehicle_arrived) will yield improvements including:

• no quoting required in SQL queries, making for easier WHERE clauses
• direct mapping to constants/enums within various programming languages
• consistency with common naming conventions in data pipelines
• alignment with other TIDES string conventions

- For reference, see related discussion in Issue #235 and Fall 2025 TIDES Issues Working Group notes from December 1 and December 10.

Review checklist

Per change management policy, the following must be met before feature branch changes can merge to develop branch:

• All JSON files validate
• Reviewed and approved by 2+ contributors or board members

[github-actions]

Documentation available at: http://tides-transit.github.io/TIDES/feature/issue-235-event-naming

[jlstpaul]

This may end up being a separate issue, but I notice that we have bike_rack_deployed, but not bike_rack_raised. We also have ramp_failed but not lift_failed.

[botanize]

Looks good to me

[CTRAN-Sutinen]

Edit: the other events tables need to be updated as well for consistency's sake. if we are going to snake_case enums in passenger events, we should be doing the same in fare events as well.