feat: add HIP-3 breadth and core L4 replay contracts

[nuttykenzo]

Summary

• Adds typed HIP-3 breadth current and cursor-paginated history access, with explicit 2026-08-28 history availability.
• Supports Hyperliquid core l4_diffs and l4_orders replay as an initial l4_snapshot followed by ordered l4_batch frames; HIP-3, HIP-4, and Spot L4 remain live-only.
• Corrects projected forced-liquidation price-level cadence to approximately five minutes and documents Lighter funding values as fractional and non-annualized.
• Preserves all six Lighter WebSocket channels as replay-only.

Validation

• cargo +1.88.0 test --all-features (49 tests and doctests passed)
• cargo +1.88.0 check --all-features
• cargo +1.88.0 package --allow-dirty --no-verify (41 files packaged)
• Focused HIP-3 breadth and WebSocket contract suites passed
• git diff --check and exact changed-path validation passed

Baseline notes

• Repository-wide cargo fmt --check is already non-green on the base; the candidate adds no formatter-only file beyond the focused new/test files, which were formatted directly.
• Strict Clippy is already non-green on the base. The candidate and base each report 26 normalized diagnostics, with no candidate-only diagnostic.

No package was published, tagged, merged, or released.