Ensure extension command additions are detected during contract review #10821

Problem

Extension contract reviews can miss a newly exposed command when its registration is added in one changed file and its constructor is implemented elsewhere. Existing guidance required inspecting changed files, but did not make tracing registrations through the command tree an explicit, auditable step.

Fix

Update the contract-review procedure to compare base and head registrations, trace command registrations to constructors and parent commands across files, and track each distinct command-tree change separately. Add regression evals for cross-file registration, multiple independent commands, and a registration refactor that preserves the public command tree.

Relates to #10820