Fix AnthropicChatOptions.timeout(Duration) being ignored outside model construction

[seeun0210]

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Summary

Fixes #6604.

AnthropicChatModel.internalCall()/internalStream() never forwarded the effective AnthropicChatOptions.getTimeout() (whether set via ChatClient.Builder.defaultOptions() or a per-request ChatClient.prompt().options(...) override) into a com.anthropic.core.RequestOptions for the underlying Anthropic Java SDK call. Both call sites always used the SDK's default RequestOptions, so the only timeout that ever had any effect was the one baked into the shared AnthropicChatModel/AnthropicClient once, at construction time (via spring.ai.anthropic.timeout). This contradicts the documented usage, which shows .timeout(Duration) as a per-call AnthropicChatOptions setting.

• Adds a requestOptionsFor(Prompt) helper that resolves the merged (default + per-request) AnthropicChatOptions.getTimeout() into an explicit RequestOptions, passed to both messageService.create(params, requestOptions) and createStreaming(params, requestOptions).
• Updates AnthropicChatModelTests' Mockito stubs to match the new two-arg SDK call signature (mechanical change, no behavior change to the tests themselves).
• Adds AnthropicChatModelTimeoutTests with 3 cases: construction-time timeout bounds a call; a per-request ChatClient timeout overrides a too-short construction-time default; a ChatClient default-options timeout overrides a too-short construction-time default. All 3 fail without the fix (verified) and pass with it.

Test plan

• ./mvnw -pl models/spring-ai-anthropic test — full module suite (123 tests) passes
• New AnthropicChatModelTimeoutTests fail without the fix (confirmed via git stash on the production change) and pass with it
• Verified no real Anthropic API calls are needed — regression tests use MockWebServer with setHeadersDelay(...) for deterministic timing

[seeun0210]

While working on this, I noticed the same pattern likely exists in other provider modules — e.g. OpenAiChatModel.internalCall()/internalStream() also call this.openAiClient.chat().completions().create(request) / .createStreaming(request) with no com.openai.core.RequestOptions argument, even though the OpenAI Java SDK exposes the same create(params, RequestOptions) two-arg overload that this fix uses for Anthropic. So OpenAiChatOptions.getTimeout() set via ChatClient (default or per-request) is probably silently ignored there too, for the same reason.

If this fix direction looks right to maintainers, I'm happy to apply the same pattern to OpenAI (and check other provider modules for the same issue) in follow-up PRs.