List activities from the local cache, most recent first.

start_date/end_date: 'YYYY-MM-DD', inclusive, optional.
activity_type: exact match against Garmin's granular activity_type
    (e.g. 'road_biking', 'gravel_cycling', 'indoor_cycling', 'treadmill_running'), optional.
sport_type: exact match against Garmin's broader sport_type grouping
    (e.g. 'CYCLING', 'RUNNING', 'WALKING') -- prefer this over activity_type
    for questions like "how many bike rides" or "how many runs", since it
    groups all the granular variants (road/gravel/indoor cycling, etc.)
    together in one filter instead of requiring you to enumerate and
    manually classify a mixed activity list yourself. Optional.

Full detail for one activity: summary row + laps + HR/power zones + gear.

Daily steps/HR/stress/body battery/SpO2/respiration for a date range (inclusive, 'YYYY-MM-DD').

Nightly sleep stages + sleep score breakdown for a date range (inclusive, 'YYYY-MM-DD').

Training status, readiness, VO2max, load (ACWR), endurance/hill scores, and race predictions for a date range (inclusive, 'YYYY-MM-DD').

Recent sync_log entries -- what's been fetched, what failed/was rate-limited, and the current resume cursors for every category. Check this before trusting 'no data' as a real gap vs. a not-yet-synced range.

Run an ad hoc read-only SQL query against the local cache. Only SELECT/WITH/EXPLAIN/PRAGMA table_info statements are allowed.

Explicitly hit the live Garmin API to pull new data since the last successful sync, for every category. Rate-limited; respects any active cooldown from a previous 429. Never called automatically by other tools.

Run one controlled batch of API-driven backfill per category, walking further back into history than the bulk export (or a prior backfill run) reached. Call repeatedly to walk the full history without one giant fetch.

`categories`, if given, restricts the batch to that subset (e.g.
["hrv_daily"]) instead of every category -- one of: activities,
daily_health_metrics, sleep, hrv_daily, training_readiness,
training_status, race_predictions, body_composition.