trackclean 0.1.0

• Initial release.
• Functions for the complete cleaning pipeline: map_ids(), mark_time_periods(), standardize_to_seconds(), interpolate_gaps(), fix_tag_replacement(), and clean_playground_data().
• Two-phase gap interpolation: phase 1 for small gaps, phase 2 for larger gaps with minimal position change.
• Configurable time interval for standardization (unit parameter) and matching interpolation step (time_step).
• All column names are user-configurable with sensible defaults.
• Bundled example dataset (10 participants, 40m x 60m space, ~13 minutes) in inst/extdata/.