[Quinn-With-Two-Ns]

What changed?

• Auto-configure a primary temporalActivityClient and namespace/alias-prefixed activity clients, following the existing ScheduleClient wiring and capabilities.
• Apply namespace data converters, root ActivityClientInterceptor beans, and ordered TemporalOptionsCustomizer<ActivityClientOptions.Builder> beans, including the existing namespace-specific naming convention.
• Add wiring and options customization tests, documentation, and a changelog entry.

Why?

Applications should be able to inject an ActivityClient without manually reproducing the Spring namespace, converter, and interceptor configuration. Invocation-specific task queues and timeouts remain in StartActivityOptions.

Fixes #3146.

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Note

Low Risk
Additive Spring Boot wiring mirroring ScheduleClient patterns; no changes to core SDK client behavior beyond new beans and constructor signature updates in autoconfigure templates.

Overview
Spring Boot Temporal integration now auto-configures ActivityClient alongside existing workflow and schedule clients, so apps can inject standalone activity clients without hand-wiring namespace, converters, and interceptors.

The root namespace gets a primary temporalActivityClient bean; each configured non-root namespace gets <alias-or-namespace>ActivityClient, registered through the same template/post-processor path as other per-namespace clients. Options are built via ActivityClientOptions with per-namespace data converters, ordered TemporalOptionsCustomizer<ActivityClientOptions.Builder> beans (including the existing *ActivityClientCustomizer naming for non-root namespaces), and root-only ActivityClientInterceptor registration (non-root interceptors via customizers). ClientTemplate lazily creates the client from shared service stubs; deprecated template constructors without activity-client parameters were removed.

Documentation, changelog, and tests cover wiring, customizer ordering, and multi-namespace beans.

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