fix: Fix estimate, usage, and job-response parsing against the live v0.4 API

[antalszava]

Fixes three runtime failures against the live v0.4 API — estimate_job_cost, get_usages, and get_job parsing — by patching stale/incorrect schemas in openapi-overlay.yaml and regenerating the client. Also unblocks committing generated output (pre-commit was rewriting it) and fixes a pytest deprecation in the integration tests.

Hand-written changes

Library

• ionq_core/polling.py — the spec's GetJobResponse component became an anyOf union, so the generator no longer emits a model class for it; replaced the dead import with a TYPE_CHECKING-only union alias over the four job types.

Spec overlay (openapi-overlay.yaml)

• GetJobEstimateResponse replaced with the shape the API actually serves (estimate_context / rate_card / estimated_total_cost / estimated_unit) — was raising KeyError: 'input_values'.
• organization_id no longer format: uuid — real org ids are reverse-DNS strings; was raising badly formed hexadecimal UUID string.
• Usage.from widened date → date-time — the API returns RFC 3339 date-times; was raising Invalid isoformat string.
• ErrorMitigationOutput.debiasing widened to anyOf boolean/object — the API serves false when debiasing is off; was surfacing as a misleading Unexpected value 'ionq.circuit.v1' from the GetJobResponse union parser.

Tooling

• .pre-commit-config.yaml — excluded generated files from trailing-whitespace / end-of-file-fixer; they were rewriting generator output at commit time and breaking the generated.yml byte-exact staleness check.
• CHANGELOG.md — "Fixed" entries for the estimate, org-id, and Usage.from bugs.

Integration tests

• conftest.py — new session-scoped base_url fixture (reads IONQ_API_URL, falls back to the default).
• test_async.py / test_backends.py — fixtures thread base_url through instead of hardcoding it.
• test_usage.py — new org_id fixture (reads IONQ_ORG_ID, skips when unset); used instead of the literal "self".
• test_simulator_job.py — completed_job_id moved from a class-scoped instance-method fixture to a module-level session fixture, fixing PytestRemovedIn10Warning: Class-scoped fixture defined as instance method is deprecated.
• test_sessions.py — accepts "created" as a valid initial session status.

Generated changes

Everything under ionq_core/api/ and ionq_core/models/ (105 files: ~50 new models from the May-2026 upstream spec sync — the SingleCircuitJob / MultiCircuitJob / QaoaJob / QuantumFunctionJob families, result formats, artifact descriptors, the new move_job and schemas endpoints — plus modifications from the overlay fixes above). Mechanical openapi-python-client output; the generated.yml staleness check reproduces it byte-for-byte, so it doesn't need line-by-line review. openapi.json is the vendored upstream spec (1-line change).

Testing

• Unit suite: 242 passed, 100% coverage on the hand-written surface.
• Integration suite against the live API: all passing except the two known test_sessions failures (sessions not enabled for project, an account limitation).

Note on AI usage

• PR description: generated by Claude;
• PR: aided by Claude.

[hodgestar-ionq]

Left some questions and comments. Thank you for all the fixes.

[antalszava]

@hodgestar-ionq thank you for the questions! I've left answers to each.

[splch]

Tested live - estimate + get_job parse fine now. LGTM, thanks! Let's land this before the scan-findings stack (plan on #95).