Add model-card YAML frontmatter (clears HF 'missing yaml metadata' warning)

Shrink: 16/32-bit MLPs -> width-matched TCN. Artifact 0.77GB -> 0.13GB

Tier 8 re-polish: 0.92 -> 0.98, overall 0.982 -> 0.988

Harden tier 10: 0.94 -> 0.98, overall 0.978 -> 0.982

Tier 10 = 0.94: highest_tier 9->10 (MAX), overall 0.886->0.978

Tier 9 = 0.99: highest_tier 8->9, overall 0.788->0.886

64-bit cell: MLP -> carry-aware TCN (fixes tier-0 near-2^64, 944MB->13MB)

Tier 8 saturated at 0.92: highest_tier 7->8, overall 0.769->0.788

Partial 512-bit cell (tier 8 = 0.73): overall 0.698 -> 0.769

Tier-7 256-bit carry-aware TCN cell: highest_tier 6->7, overall 0.602->0.698, tier-7 0.98

Tier-6 carry-aware TCN cell: highest_tier 5->6, overall 0.531->0.602, tier-6 0.97

Update card + manifest: tier 5 0.74 -> 0.98 (trajectory training), highest_tier_above_90 5

Update tier-5 metrics to 0.74 (overall 0.483); refresh 64-bit compliance row

Horner-RNN modular-multiplication model (tiers 1-5, up to 2^64)