refactor: Tour de Force is Acts 1-5 only; engine capabilities move to domain registry (#29)

Tour de Force (tour_de_force.py, render_html.py): - Strip Acts 6-9 entirely — demo is now a clean 5-act music story (41 ops) - Remove OT-branch BRANCH_COLORS and act 6-9 ACT_TITLES entries - Remove buildDomainSection(), buildCRDTSection(), RICH_ACTS, CRDT_ACT JS - Replace domain/CRDT sections with a single registry callout banner ("Want to version something else? → Domain Registry & Plugin Guide") - Act jump bar, reveal-all, per-act icons still work for acts 1-5

Domain Registry (render_domain_registry.py): - Add _compute_crdt_demos() — runs ORSet/LWWRegister/GCounter/VectorClock live - Add _TYPED_DELTA_EXAMPLE and _OT_MERGE_EXAMPLE static accurate examples - Add Engine Capabilities section (4 full-width cards before the Build section): - Typed Delta Algebra: muse show --json output explained - Domain Schema: live domain cards from muse domains --json - OT Merge: both scenarios (commuting inserts + same-address conflict) - CRDT Primitives: four live demo cards computed at render time - Add cap-showcase-grid CSS with card, header, badge, output styles

Co-authored-by: Gabriel Cardona <gabriel@tellurstori.com>