[codeministry]

Replaces the openai-java hold at 4.65.0 with a fix on our side, so #55 is no longer needed.

Cause

From openai-java 4.66.0 on (openai/openai-java#1027), StreamResponse.close() closes the OkHttp response before the reader. A chat turn is stopped, deleted or timed out by closing its stream from a thread other than the one blocked reading it. That close then runs under the read still in flight: okio throws "Unbalanced enter/exit", the socket stays open, and the model keeps generating an answer nobody reads.

Fix

• llm/CancelOnClose, an OkHttp interceptor: closing a response body calls Call.cancel() first, which is OkHttp's own thread-safe way to end a call from outside.
• ChatModels hands it to the sync and the async OpenAI client through OpenAiSetup's customizer list.
• A body that was read to its end has nothing left to cancel, so the judge and the classifier, which call rather than stream, are unaffected.
• The strictly constraint, the openaiJava catalog entry and openai-java's own Renovate rule are gone. openai-java comes from the Spring AI BOM again (4.80.0).
• docs/decisions/chat.md § Stop and regenerate has the reasoning, backend/CLAUDE.md a one-line rule, and the CHANGELOG is corrected.

Verification

• Without the interceptor, on 4.80.0: ChatStreamTest, ChatTurnDeadlineTest and two ChatConversationTest cases are red ("the stub saw its connection closed", "the model call was cancelled").
• With it: green on 4.80.0, and on 4.101.0 with a temporary constraint.
• ./gradlew build: 1304 backend cases, 96 unit and 22 browser test files, all green; the 13 skipped are the corpus tests without .eml samples.
• No "Unbalanced" in any test report.

After the merge, #55 points at a catalog entry that no longer exists and can be closed.