Per sub-project-2 plan Task 2 / spec §3. Purely additive to hef.catalog;
no existing symbol changes. validate_catalog runs per-record validate() then
asserts id uniqueness; index_by_id gives by-id lookup the player also wants.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Per sub-project-2 plan Task 1. Adds tools/ to setuptools packages,
gitignores media/, and a minimal injectable urllib HTTP client.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Ben Stull