[DABH]

Add native Java ADK samples for the published Public Preview io.temporal:google-adk:0.1.0 integration. Agent Chat is the introductory sample and the default starter command; remove the separate single-turn basic sample.

The nine scenarios cover conversation state and Continue-As-New, deterministic and Activity tools, stateless Java MCP over stdio, human approval, structured output, native parallel agents, long-running tool callbacks, buffered SSE output over Workflow Streams, and OpenTelemetry tracing of Temporal operations. Each has live Gemini and credential-free offline modes using the same plugin, Worker, Workflows, Activities, and message paths.

The streaming sample preserves ADK partial/final events and publishes them after the model Activity completes; it does not claim live token forwarding. Its subscriber acknowledges completion, and a run with no subscriber finishes after a bounded deadline. The tracing sample links model and tool Activity spans, shows failed/retried attempts, and filters replayed Workflow spans before export. It does not enable native ADK's global tracing provider.

All scenarios have CLI instructions and targeted tests. The documentation companion uses 19 snippets from tested commit a4ef743 and stays in draft until this PR merges. The module uses published Maven dependencies and an explicit Temporal SDK/testing constraint of [1.40.0,2.0), preferring 1.40.0.

Validation:

• Java 17/macOS: all 31 ADK tests, module build, repository-wide formatting, and full repository tests pass.
• Java 17/Linux: all 31 ADK tests and the module build pass with Docker networking disabled and Gradle in offline mode after dependencies are cached.
• A real local Temporal Service and credential-free Worker verify the default chat starter, message/query/finish commands, streaming subscriber, no-subscriber completion, and console tracing with shared trace identifiers.
• Tests verify Activity boundaries, retries/failures, schema validation, approvals/cancellation, session/queue carry, stream ordering, telemetry linkage, and fresh-Worker replay without repeated model/tool calls or extra spans.
• git diff --check passes. Live Gemini was not exercised.