[huangji6693-max]

Summary

Adds an admin-authorized contract upgrade path (upgrade) alongside explicit storage-layout schema versioning (DataKey::StorageVersion) and a state migration routine (migrate) that safely transforms legacy v1 escrow and dispute records to the current v2 schema.

Closes #41

Changes

• Storage-Layout Versioning:
  • Added STORAGE_VERSION_V1 = 1 and CURRENT_STORAGE_VERSION = 2 constants and DataKey::StorageVersion (set on initialize, queried via get_storage_version).
• Authorized In-Place WASM Upgrade:
  • Added upgrade(env, caller, new_wasm_hash) entrypoint restricted to the contract Admin, invoking env.deployer().update_current_contract_wasm(new_wasm_hash) and emitting a ContractUpgraded event ((symbol_short!("contract"), symbol_short!("upgraded"))).
• State Migration Routine (migrate):
  • Added legacy schema types (MilestoneV1, EscrowRecordV1, DisputeRecordV1) and DataKey::LegacyEscrowV1(u64) / DataKey::LegacyDisputeV1(u64).
  • Implemented admin-only migrate(env, caller) -> Result<u32, TrustFlowError> that guards against redundant runs (TrustFlowError::AlreadyAtLatestVersion), backfills missing FeeBps/Treasury defaults, transforms v1 escrows (MilestoneV1 -> Milestone with release_time: 0) and missing EscrowFeeConfig snapshots, transforms v1 disputes with commit/reveal deadlines, bumps persistent TTLs, updates DataKey::StorageVersion to CURRENT_STORAGE_VERSION, and emits a StorageMigrated event ((symbol_short!("storage"), symbol_short!("migrated"))).
• Unit Tests:
  • Added tests covering version initialization, unauthorized upgrade/migrate rejection, AlreadyAtLatestVersion guard, and end-to-end v1 -> v2 escrow + dispute migration followed by milestone tranche release.

Verification

• [MEASURED] cargo test --package trustflow: 68 passed; 0 failed
• [MEASURED] cargo build --target wasm32-unknown-unknown --release --package trustflow: succeeded
• [MEASURED] cargo fmt --all --check & cargo clippy --all-features --workspace --lib: passed