specs/hosting/proof.t27: state the dissent rule in side_of instead of copying verifier_dissented #8731

Follow-up to #8707 (PR #8720, merged). specs/hosting/proof.t27 carries a word-for-word copy of network/mvp_v2.t27's verifier_dissented. The duplicate-bodies gate flagged it on #8720 as a new copy that is in no ledger.

The copy was there for a reason. Importing from mvp_v2.t27 splices its SHA-256 into the card. t27c pulls every declaration whose name appears anywhere in the importing file, comments included, and gen-c cannot lower that SHA-256 code.

The fix: side_of states the rule itself for this card's verdicts (a vote dissents only from an agreed job). mvp_v2_rules_are_kept keeps pinning it to mvp_v2.t27's own asserts. After the change, the scan lists only master's own groups: bits, same and clear.

User Scenarios

• Given the specs/hosting/proof.t27 file contains a word-for-word copy of verifier_dissented from network/mvp_v2.t27, When the duplicate-bodies gate runs, Then it flags the copy as a new duplicate not in any ledger.
• Given the copy exists because importing from mvp_v2.t27 splices its SHA-256 into the card which gen-c cannot lower, When the dissent rule is restated locally using side_of and pinned via mvp_v2_rules_are_kept, Then the scan lists only master's own groups: bits, same, and clear.

Requirements

• FR-001: The specs/hosting/proof.t27 file MUST restate the dissent rule using side_of for this card's verdicts (a vote dissents only from an agreed job).
• FR-002: The specs/hosting/proof.t27 file MUST keep mvp_v2_rules_are_kept to pin the rule to mvp_v2.t27's own asserts.
• FR-003: The word-for-word copy of verifier_dissented from network/mvp_v2.t27 MUST be removed from specs/hosting/proof.t27.

Success Criteria

• The duplicate-bodies gate passes on specs/hosting/proof.t27 (exit 0)
• The scan of specs/hosting/proof.t27 lists only the groups bits, same, and clear (3 groups)
• The command t27c specs/hosting/proof.t27 compiles without errors (exit 0)

Boundary

• specs/hosting/proof.t27