refactor: replace submodule with local testing framework

[RonTuretzky]

Summary

• Remove foundry-counter submodule and integration-test.yml
• Add local test framework in tests/ and scripts/
• Rename workflow titles for clarity
• Add test.yml workflow to run tests in CI
• Update README with new testing approach

Workflow Name Changes

Old Name	New Name
Foundry CI	Build & Test
Foundry CI/CD	CI/CD Pipeline
Deploy	Deploy & Verify
Detect Changes	Detect Contract Changes
Post Mainnet	Post-Deploy Snapshots
Upgrade Safety	Upgrade Safety Check

Testing Approach

The workflow logic is tested by extracting testable shell functions into standalone scripts, then running them against test fixtures that cover success and failure cases.

Why This Approach?

1. No external dependencies: Tests run locally without needing a real Foundry project
2. Fast feedback: Shell scripts run instantly vs. waiting for GitHub Actions
3. Complete coverage: Can test failure cases that would be hard to trigger in integration tests
4. Reproducible: Same tests run locally and in CI

Running Tests

./tests/run-all.sh

Test Coverage

Test Suite	Validates
test-compiler-config.sh	bytecode_hash and cbor_metadata validation
test-baseline-detection.sh	Baseline directory detection and fallback logic