ci: add automated test CI for KeyRA 🐙

[Klazomenai]

Summary

Add GitHub Actions CI to run all 42 existing KeyRA tests automatically on push and PR.

Background

KeyRA has comprehensive test coverage (4 unit + 12 integration + 3 E2E Rust + 23 Solidity Foundry) but zero CI. All tests are run locally only. This epic adds automated test execution.

Goals

• Automated Rust unit + integration tests on every push/PR
• Automated Solidity Foundry tests on every push/PR
• Automated E2E tests with Anvil (Foundry's dev node) on every push/PR
• Fix silent E2E test skip to prevent false positives in CI
• Optional Autonity-specific E2E job (future)

Sub-Issues

• ci: add CI workflow for Rust unit and integration tests 🏗️ #3 ci: add CI workflow for Rust unit and integration tests 🏗️
• ci: add CI job for Solidity Foundry tests 🏗️ #4 ci: add CI job for Solidity Foundry tests 🏗️
• fix: make E2E tests fail-loud in CI instead of silently skipping 🐛 #5 fix: make E2E tests fail-loud in CI instead of silently skipping 🐛
• test: verify E2E test compatibility with Anvil 🧪 #6 test: verify E2E test compatibility with Anvil 🧪
• ci: add CI job for E2E tests with Anvil 🏗️ #7 ci: add CI job for E2E tests with Anvil 🏗️
• ci: add optional Autonity E2E test job 🏗️ #8 ci: add optional Autonity E2E test job 🏗️

Execution Order

1. #3 (Rust unit + integration)  — standalone, no external deps ✅
2. #4 (Solidity Foundry)         — standalone, needs forge
3. #5 (fail-loud fix)            — standalone code change
4. #6 (Anvil verification)       — depends on #5
5. #7 (E2E with Anvil)           — depends on #4, #5, #6
6. #8 (Autonity E2E)             — depends on #7, future scope

Test Inventory

Category	Count	Command	External Deps
Rust unit	4	cargo test --lib	None
Rust integration	12	cargo test --test integration	None
Rust E2E	3	cargo test --test e2e	EVM node + forge artifacts
Solidity Foundry	23	cd contracts && forge test	Foundry
Total	42

Acceptance Criteria

• All 42 tests run automatically on push to main and on PRs
• E2E tests FAIL (not skip) when EVM node is unavailable in CI
• CI badge in README
• Green CI on current main branch