chore(lint): enable unicorn/no-immediate-mutation

[HAYDEN-OAI]

• I understand that this repository is auto-generated and my pull request may not be merged

Changes being requested

• Remove the unicorn/no-immediate-mutation compatibility exception from oxlint.config.ts.
• Baseline: 1 handwritten-code violation on main.
• Apply safe Ultracite autofixes and focused, behavior-preserving handwritten-code cleanup.

Additional context & links

• Oxlint cleanup stack, part 42; stacked on chore(lint): enable unicorn/error-message #2115.
• Preserves Stainless-generated-file exclusions and repository-specific import policy.

Validation

• Ultracite 7.8.4 formatting and lint check.
• TypeScript 6.0.3 type check.
• Complete handwritten Vitest suite.

Stack

#2090
#2091
#2092
#2093
#2094
#2095
#2096
#2097
#2098
#2099
#2100
#2101
#2102
#2103
#2104
#2105
#2106
#2107
#2108
#2109
#2110
#2111
#2112
#2113
#2114
#2115
#2116 👈 this PR
#2117
#2118
#2119
#2120
#2121
#2122
#2123

[openai-sdks]

OkTest Summary

✅ 237/237 SDK tests passed in 10.402s for Node SDK PR #2116.

Test results — 42 files

Test	Result	Time
tests/chat-completions-complex-body.test.ts	✅ Passed	208ms
tests/chat-completions-create.test.ts	✅ Passed	211ms
tests/chat-completions-stream.test.ts	✅ Passed	271ms
tests/files-content-binary.test.ts	✅ Passed	136ms
tests/files-create-multipart.test.ts	✅ Passed	181ms
tests/files-list-pagination.test.ts	✅ Passed	158ms
tests/initialize-config.test.ts	✅ Passed	164ms
tests/instance-isolation.test.ts	✅ Passed	108ms
tests/models-list.test.ts	✅ Passed	133ms
tests/responses-background-lifecycle.test.ts	✅ Passed	241ms
tests/responses-body-method-errors.test.ts	✅ Passed	296ms
tests/responses-cancel-timeout.test.ts	✅ Passed	189ms
tests/responses-cancel.test.ts	✅ Passed	238ms
tests/responses-compact-retries.test.ts	✅ Passed	283ms
tests/responses-compact.test.ts	✅ Passed	224ms
tests/responses-create-advanced-stream.test.ts	✅ Passed	125ms
tests/responses-create-advanced.test.ts	✅ Passed	225ms
tests/responses-create-disconnect.test.ts	✅ Passed	1.204s
tests/responses-create-errors.test.ts	✅ Passed	214ms
tests/responses-create-malformed-api-responses.test.ts	✅ Passed	143ms
tests/responses-create-retries.test.ts	✅ Passed	280ms
tests/responses-create-stream-failures.test.ts	✅ Passed	214ms
tests/responses-create-stream-timeout.test.ts	✅ Passed	2.152s
tests/responses-create-stream-wire.test.ts	✅ Passed	2.587s
tests/responses-create-stream.test.ts	✅ Passed	86ms
tests/responses-create-terminal-states.test.ts	✅ Passed	230ms
tests/responses-create-timeout.test.ts	✅ Passed	200ms
tests/responses-create.test.ts	✅ Passed	140ms
tests/responses-delete.test.ts	✅ Passed	239ms
tests/responses-input-items-errors.test.ts	✅ Passed	274ms
tests/responses-input-items-list.test.ts	✅ Passed	176ms
tests/responses-input-items-options.test.ts	✅ Passed	120ms
tests/responses-input-tokens-count-timeout.test.ts	✅ Passed	231ms
tests/responses-input-tokens-count.test.ts	✅ Passed	269ms
tests/responses-malformed-inputs.test.ts	✅ Passed	2.269s
tests/responses-not-found-errors.test.ts	✅ Passed	231ms
tests/responses-parse.test.ts	✅ Passed	171ms
tests/responses-retrieve-retries.test.ts	✅ Passed	212ms
tests/responses-retrieve.test.ts	✅ Passed	181ms
tests/responses-stored-method-errors.test.ts	✅ Passed	564ms
tests/retry-behavior.test.ts	✅ Passed	2.808s
tests/sdk-error-shape.test.ts	✅ Passed	277ms

View OkTest run #31211009601

_{SDK merge (11ae95b7a092) · head (c64d63b2153b) · base (61f47a85991e) · OkTest (91635c6a2723)}