Usage: photoc [global options] timeline <directory> [--recursive] [--gap <duration>] [--json]
       photoc timeline --help

Summarize shooting dates and sessions

Status: read-only JPEG and Sony ARW metadata

Example:
  photoc timeline ~/Pictures/Prague
  photoc timeline ~/Pictures/Prague --recursive --gap 30m
  photoc timeline ~/Pictures/Prague --gap 2h --json

Options:
  --recursive          Include nested directories
  --gap <duration>     Session gap (for example 30m or 2h; default 60m)
  --json               Print date/session hierarchy and scan summary

Group by recorded calendar date, then capture-time session.
An exact gap stays in one session; midnight always starts another.
Missing/invalid capture times are counted and excluded; no timezone is inferred.
