Add a bats (or mocked-curl) test covering the offline-reclaim and online-refuse branches #159

What

Add an automated test that exercises the two branches of reclaim_orphaned_name() in entrypoint.sh:

1. Offline-reclaim branch — a same-named runner is listed with status == "offline", so the function issues a DELETE and returns success.
2. Online-refuse branch — a same-named runner is listed with a non-offline status, so the function does not delete and the entrypoint refuses to start (preserving the deliberate no---replace stance).

The test must not require a live GitHub repo or network access.

Why

The reclaim logic is the core of PR #154 and its two decision branches are exactly the kind of behaviour that silently regresses: a future refactor of the jq extraction, the [[ -n "${id}" ]] guard, or the status comparison could flip the online-refuse branch into a delete and nobody would notice until a live runner was clobbered. The manual reproduce steps in the original issue (hard-kill, restart, observe crashloop) require a live repo and a rate-limited host, so they are not a regression guard. A bats test (or a shell test with a mocked curl) pins both branches down cheaply.

How

• Add a bats test file (e.g. test/entrypoint.bats) or, if bats is not acceptable as a dev dependency, a plain shell test that sources entrypoint.sh with a mocked curl on PATH.
• Mock curl so that:
  • The listing call (GET /actions/runners) returns a JSON body containing a single runner with the same RUNNER_NAME and a controllable status.
  • The DELETE call records that it was invoked (e.g. writes to a temp file) and returns a success status.
• Case 1 (offline): assert the mock DELETE was invoked exactly once and the function returned success.
• Case 2 (online): assert the mock DELETE was not invoked and the entrypoint exits non-zero / refuses to start.
• Keep the mock minimal — only the endpoints reclaim_orphaned_name() actually calls need to be stubbed. Do not attempt to mock the full registration flow.
• If bats is used, add a short note to the repo's test docs (or the PR description) on how to run it locally.

Files Affected

• entrypoint.sh (source under test; no changes required unless a seam is needed to make it sourceable)
• test/entrypoint.bats (new — or an equivalent shell test path if bats is not adopted)
• Unknown (test runner config / CI workflow, if one exists and needs to invoke the new test)

Constraints

• Must not require network access, a live GitHub repo, or a real PAT.
• Must not change the runtime behaviour of entrypoint.sh; this is test-only. If a small refactor is needed to make the function sourceable/testable, it must be behaviour-preserving.
• Out of scope: the other follow-ups from the same review (the unconditional rm -f .runner, the command -v jq guard, the single-pass jq extraction, Retry-After handling). Those are separate issues.
• Out of scope: testing the jq-missing silent no-op path — that is covered by the separate jq guard follow-up.

LLM tier

Sonnet — new test coverage requiring design decisions (how to mock curl, how to make the entrypoint sourceable, what to assert), but no architectural ambiguity.

Success looks like

• A test exists that fails if the offline branch stops issuing the DELETE.
• A test exists that fails if the online branch starts issuing a DELETE (or stops refusing to start).
• Both tests pass on the current entrypoint.sh from PR Reclaim our own offline registration instead of crashlooping on it #154.
• The tests run without network access and without a GitHub token.
• Running the test suite is documented (command + any prerequisites).

Failure looks like

• Tests that only assert the function "ran" without checking whether DELETE was called — they would pass on both branches and guard nothing.
• Tests that require a live repo, a real token, or network access.
• A refactor of entrypoint.sh that changes runtime behaviour in order to make it testable.
• The online-refuse case being tested only by asserting a non-zero exit, without asserting that no DELETE was issued.

Follow-up from AI review of PR #154.