expand mudra scope: clock, vdf, location

problem

bbg reference specifies algorithms that have no implementation home:

VDF (verifiable delay function) — rate-limits signal creation

hash chain — per-neuron prev links, equivocation detection

merkle clock — compact causal DAG commitment

step counter — monotonic logical clock per neuron

deterministic tiebreak — H(A) < H(B) for concurrent signals

location proof — RTT mesh + classical MDS → 3D coordinates

these are all cryptographic primitives that prove properties:

vdf proves delay (physical time without clocks)

clock proves ordering (causal, logical, physical)

location proves position (geometric consistency)

they belong in mudra alongside existing modules (kem, ctidh, tfhe, threshold).

changes

1. CLAUDE.md — update modules section

add three new modules to the modules list and security boundaries table:

vdf/ — verifiable delay function (sequential squaring assumption)

clock/ — hash chain + merkle clock + step counter + tiebreak

location/ — RTT + MDS location proof (speed-of-light bound)

2. Cargo.toml — update description

from: "post-quantum cryptographic primitives: KEM, dCTIDH, TFHE, threshold" to: "cryptographic primitives: KEM, dCTIDH, TFHE, threshold, VDF, clock, location"

3. README.md — update

expand single-line description to reflect full scope.

4. reference/ — create specs for new modules

reference/vdf.md — VDF specification (from bbg/reference/sync.md)

reference/clock.md — hash chain + merkle clock + step + tiebreak

reference/location.md — RTT + MDS location proof

5. src/lib.rs — declare modules

add module declarations (empty for now, spec before code).

what does NOT change

existing module specs (kem, ctidh, tfhe, threshold) — untouched

Cargo.toml dependencies — no new deps needed

security boundary principle — each module independent