labeling node backend refactor for frontend fields

[itang06]

What?

Updated the time_labels backend to support additional fields required by the frontend:

• Renamed timestamp to start_timestamp
• Added end_timestamp (nullable for in progress labels)
• Added color (required) to store the label's display color

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How?

Migration (update_time_labels.sql):

• Renames timestamp to start_timestamp
• Adds nullable end_timestamp TIMESTAMPTZ
• Adds color TEXT NOT NULL

Models (models.rs):

• Updated TimeLabel and NewTimeLabel structs to include start_timestamp, end_timestamp (as Option<DateTime>), and color

DB functions (db.rs):

• insert_time_labels(); updated column list and bindings to include new fields
• get_time_labels_by_range(); updated SELECT and WHERE to use start_timestamp

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Testing

Postman testing:

1. POST /api/sessions - created session to get a valid session_id

2. POST /api/sessions/:id/time-label - 201 response, posted first label with start_timestamp, end_timestamp, label, and color

3. POST /api/sessions/:id/time-label - 201 response, posted second label with end_timestamp: null to verify nullable case

4. GET /api/sessions/:id/time-label?start=...&end=... - wide time range returns both labels, including the one with null

5. GET /api/sessions/:id/time-label?start=...&end=... - narrow range starting after the first label ends returns only the second

[github-actions]

✅ PR approval conditions satisfied (1 lead OR 2 team members approved).
[Last checked: 2026-03-15T17:44:59.557Z]

[HeisSteve]

LGTM