Tested the pins and one end-to-end run in a new CI workflow

[DEVANSH-DVJ]

Closes #47
Closes #48

• tests/check_versions.py exits non-zero, naming each difference, unless every place that names a version agrees: each pin of pyproject.toml with the newest row of the README's compatibility table and with the installed package, the package's version with the installed act-ecosystem and with the image tag of the four docker scripts, the newest row's image cell with its ACT cell, and docker/act-env.env with the Python and JAX that run.
• It fails as well when a cell in the newest row does not link the release it names, when two rows name one ACT release, and when pip check fails.
• tests/test_end_to_end.py declares a three-instruction accelerator through act.taidl, generates its oracle and its backend through act.generators, compiles a 4x4 matrix product with the backend and simulates the assembly on the oracle, whose output must equal the product exactly.
• tests/pytest.sh runs the test in the ecosystem image through docker/exec.sh, with no .pytest_cache left in the tree, and --platform GPU simulates on an NVIDIA GPU.
• .github/workflows/test.yml runs three steps on pushes and pull requests to master, on an amd64 and an arm64 runner: docker/build.sh --cpu, the version check and the test; the README gains a Testing section, whose build is docker/build.sh --rebuild, so the checks never run in an image an earlier tree built.
• With any one of those places changed, thirteen states in all, the version check fails, and with the pins at TAIDL-TO v2.2 and ACT-Backend v1.2 the test fails; the three steps pass on amd64 and arm64, and the test passes on a GPU in the cuda13 image on arm64.