v0.2.0

Added

• Threat model (14): network observer, malicious validator minority, dishonest majority, connection contract bug, swap counterparty, device compromise, and what is out of scope.
• Key derivation tree, epoch and range scoping, disclosure levels, credential structure, presentation and credential revocation approach in 08. Closes #4.
• Timelock and refund parameter table for Monero swaps, online requirements, and griefing mitigations in 11, with figures taken from the reference calculator at https://github.com/HashChainL0/xmr-swap-model. Closes #5.
• Glossary entries: connection contract, connection verifier, counterparty, epoch, ETH holder, XMR holder, griefing, issuer, nullifier key, receiving key, revocation, spending key, storage node, swap contract, validator set, verifier, watchtower.

Changed

• Terminology aligned with the glossary: "bridge contract" is now "connection contract" throughout, and Hash Chain itself is still described as not a bridge. Closes #8.
• Swap deadlines T0 and T1 are measured from the finalized ETH lock, and claims at or after T1 are rejected.
• Security and trust, README index and swap docs link to the threat model and the parameters.

Fixed

• Duplicated title text in the hub diagram.
• Swap sequence diagram label now matches the contract rules: refund is possible at any time after the lock.