Remove CryticToFoundry assertion shim and rely on fail_on_assert

[aviggiano]

Summary

• remove the CryticToFoundry assertion-failures shim introduced as a workaround for foundry-rs/foundry#13322
• enable fail_on_assert = true in foundry.toml
• make assertion failures explicit via assert(false) in counter_increment catch path
• remove the synthetic invariant_counter_increment campaign
• update script/ci/check_fuzzer.sh Foundry check to require:
  • invariant_number_is_small() failure
  • invariant_number_change_requires_sequence() failure
  • emitted assertion failure line containing assertion failure in counter_increment

Validation

Using local forge from Foundry (with the pending assertion-emission changes):

• ../foundry/target/debug/forge test --mc CryticToFoundry
• PATH=../foundry/target/debug:$PATH FOUNDRY_INVARIANT_CONTINUOUS_RUN=false script/ci/check_fuzzer.sh foundry

Observed in logs:

• assertion failure emitted as assertion failure in counter_increment ...
• invariant_number_change_requires_sequence() fails
• invariant_number_is_small() fails

Blocker

This PR is blocked by (and intended to land with) the Foundry fix for:

• Report assertion failures as broken invariants foundry-rs/foundry#13322