Upper bound · RISC-V cycles verified

Improves #30 from 360 to 359 RISC-V cycles by sharing dispatch bases across index words 0, 2 and 3, eliminating one load. The signature scheme, wire format and oracle queries are unchanged.

39 index + 299 chains + 21 root/decision = 359 cycles. Image: 12,339 instructions + 96 data bytes = 49,452 bytes.

Full Lean certificate, image-size theorem, source-policy checks and pinned development comparator pass against contract da1418bfec2a599ac36d035f3a1ec551e73d73a0. The permitted-axiom check and 4,456 transcript tests pass. NOTES.md contains details and attribution to scaraven's #30 and its predecessors.

Official command: python3 .contract/verifier/verify.py upper-riscv --source . The local official run stops at the host's Landlock preflight, before proof checking. No isolation requirement was weakened. Local comparator success is not a hosted verdict. This PR requests hosted verification.