test: add coverage for carbon credits, funding round, bridge, cap, governance, archive (Closes #318, #319, #320, #321, #326, #327)

[laurentketterle-hub]

Summary

Adds unit-test coverage for six previously-untested code paths and repairs the build breakage from #342 that prevented the suite from compiling.

Test coverage added

• Carbon credit feature (~140 lines) has essentially no test coverage #318 Carbon credits — calculate_carbon_credits correctness, zero-green-impact, issue_carbon_credits (success + "no carbon credits" panic), transfer_carbon_credits (success + insufficient-balance + zero-amount panics), balance query.
• Funding-round transfer block has zero test coverage #319 Funding round — start_funding_round/end_funding_round/is_funding_round_active, share-transfer panic while open, transfer succeeds after close.
• Outbound Wormhole bridge path (initiate_bridge_transfer) has zero test coverage #320 Wormhole bridge — serialize_bridge_payload/parse_bridge_payload round-trip (all fields), initiate_bridge_transfer burns HBS + publishes via a mock core, amount <= 0 panic.
• Per-project investment cap (investment_capacity/set_max_investment_per_project) has no test coverage #321 Investment cap — set_max_investment_per_project, investment_capacity before/after funding, funding at cap succeeds, 1 stroop over cap panics, cap = 0 restores the compile-time default.
• Governance proposal system (create_proposal/cast_vote/execute_proposal) has zero test coverage #326 Governance — create_proposal (happy + VotingPeriodTooShort), cast_vote (tally, weight <= 0, double-vote, VotingPeriodEnded), execute_proposal (VotingStillOpen, double-execute, pass vs. fail), get_proposal (ProposalNotFound).
• Project archive/delete/compact lifecycle has no functional test coverage (only an auth-rejection test) #327 Archive/delete/compact — archive_project status + listing exclusion, delete_project removal, compact_archive summary + ProjectNotArchived guard.

Build repairs (required for the suite to compile after #342)

• Close missing braces in lib.rs, events.rs, and test.rs.
• Resolve duplicate VaultError discriminants (FundingRoundActive/InvestmentCapExceeded).
• Restore the sequence-based deposit lock in lock_deposit/check_deposit_lock ([Logic] Implement withdrawal sliding window to prevent instant exit #36), matching the WithdrawalWindowLedgers sliding-window semantics the tests exercise.
• Update stale create_project call sites to the current 4-arg signature.
• Restore the bodies of test_get_all_project_investments_returns_all and test_claim_queued_is_idempotent_against_double_claim.
• Remove the redundant from.require_auth() before Base::burn in bridge_burn/initiate_bridge_transfer (consistent with withdraw, where Base::burn already requires auth).

Verification

• cargo test -p investment-vault — all new + existing tests pass (12 new vault tests, 21 withdraw tests).
• cargo test -p project-registry — all new + existing tests pass (15 tests).

Signed-off-by: laurentketterle-hub laurentketterle-hub@users.noreply.github.com