fix: satisfy Chonk num_circuits >= 4 assertion in mock IVC creation (#22188)

## Summary
PR #22181 tightened the `Chonk` constructor to require `num_circuits >=
4`, but `create_mock_chonk_from_constraints()` was passing
`constraints.size()` (1-2 for most kernels), causing assertion failures
during VK generation for `mock-protocol-circuits` and
`noir-protocol-circuits`.

## Fix
Pass `std::max(constraints.size(), 4)` since the mock doesn't use
`num_circuits` for anything — it directly manipulates the verification
queue.

## Verification
- All DSL tests pass (Hypernova, MockVerifier, ChonkRecursion)
- `mock-protocol-circuits` bootstrap: 11/11 circuits pass
- `noir-protocol-circuits` bootstrap: 120/120 circuits pass

ClaudeBox log: https://claudebox.work/s/71d20ef48c81e6e3?run=1

Author: AztecBot

barretenberg/cpp/src/barretenberg/dsl/acir_format/hypernova_recursion_constraint.cpp

@@ -31,7 +31,7 @@ using namespace bb;
  */
 std::shared_ptr<Chonk> create_mock_chonk_from_constraints(const std::vector<RecursionConstraint>& constraints)
 {
-    auto ivc = std::make_shared<Chonk>(constraints.size());
+    auto ivc = std::make_shared<Chonk>(std::max(constraints.size(), static_cast<size_t>(4)));
 
     // Check constraint proof type. Throws if proof_type is not a valid HyperNova type
     auto constraint_has_type = [](const RecursionConstraint& c, Chonk::QUEUE_TYPE expected) {