test(e2e): fix mypy Optional narrowing in test_session_runtime

[seant-aws]

What was the problem/requirement? (What/Why)

hatch run e2e:lint (the e2e hatch env's ruff + mypy over test/e2e) is a separate lint gate that CI never ran, so a mypy error in the e2e tests reached mainline and broke the release publish step. The standard hatch run lint in CI covers src/test/unit, not test/e2e.

What was the solution? (How)

Two changes:

1. Fix the mypy error. test/e2e/test_session_runtime.py passed worker.worker_id (str | None) to is_worker_started(worker_id: str). It is narrowed with an assert ... is not None in the enclosing scope, but the call sits inside the wait_worker_started() backoff closure, where mypy re-widens the Optional. Added the assert inside the closure, matching the existing idiom in test_worker_status.py.
2. Run e2e:lint in CI. Added an E2E Lint job to the Code Quality workflow that runs hatch run e2e:lint on every PR and mainline push, so this class of error is caught going forward. The job only lints/type-checks (no AWS credentials, no live e2e run).

What is the impact of this change?

Test/CI-only. No runtime or shipped-code change. PRs now run ruff + mypy over test/e2e.

How was this change tested?

hatch run e2e:lint locally: ruff check "All checks passed", ruff format --check "15 files already formatted", mypy "Success: no issues found in 15 source files". Workflow YAML validated (parses; jobs: UnitTest, IntegrationTests, E2ELint). The new job also runs on this PR.

Was this change documented?

No; test/CI-only.

Is this a breaking change?

No.

[github-actions]

This narrowing assert now lives inside a closure decorated with @backoff.on_exception(backoff.constant, Exception, max_time=120, interval=10), so it is caught and retried like a transient failure. If worker.worker_id were ever None, this would burn the full 120s retry window and then surface as a bare AssertionError with no message, rather than failing fast with a clear cause.

Note also that line 531 already does assert worker.worker_id is not None immediately above — mypy just does not carry narrowing of a member expression into a nested function body, which is why the duplicate is needed here.

A cleaner fix that satisfies mypy without putting a non-retryable precondition inside the retry loop is to bind a local before the closure:

worker_id = worker.worker_id
assert worker_id is not None

@backoff.on_exception(backoff.constant, Exception, max_time=120, interval=10)
def wait_worker_started() -> None:
    assert is_worker_started(
        deadline_client=deadline_client,
        farm_id=deadline_resources.farm.id,
        fleet_id=deadline_resources.fleet.id,
        worker_id=worker_id,
    )

A local variable stays narrowed inside the closure, so the assert is checked once, up front, and the duplication on line 531 goes away.

[github-actions]

Pinning this gate to a single interpreter means the e2e type check only ever runs one of the two mypy tracks the repo supports. requirements-e2e.txt splits on interpreter version:

mypy >= 2.3.0, < 2.4; python_version >= "3.10"
mypy >= 1.19.1, < 1.20; python_version < "3.10"

so CI will only exercise mypy 2.3 under 3.11, while a contributor on 3.9 gets mypy 1.19 locally. Separately, test/e2e/mypy.ini sets no python_version, so mypy infers 3.11 from the running interpreter — version-conditional typing errors under the project minimum (requires-python = ">=3.9") will not be caught here.

Two options depending on intent: either add python_version = 3.9 to test/e2e/mypy.ini so the check is pinned to the floor regardless of which interpreter CI happens to use, or give this job the same python-version matrix as UnitTest/IntegrationTests above so both mypy tracks are covered. The former is cheaper and probably sufficient; the ruff half of e2e:lint is version-independent either way.