Audit and fix all template variable references:
- template_vars.py: Add missing fields (album_id, old_shared,
new_shared, latitude, longitude, owner_id, people per asset)
- _SAMPLE_CONTEXT: Use proper structured data matching
build_asset_detail() output (id, owner_id, latitude, longitude,
people per asset, playback_url for videos)
- i18n: Fix all variable descriptions for accuracy, add missing
fields, mark scheduler-dependent slots as "not yet implemented"
- Variables modal: Add album_fields section for periodic_summary
- Shared _ASSET_FIELDS and _ALBUM_FIELDS dicts in template_vars.py
to keep scheduled/memory slots DRY
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
