chore(main): release 0.4.0

[release-please]

🤖 I have created a release beep boop

0.4.0 (2026-09-01)

Features

• Add a top-level client.sandboxes accessor to the Vertex AI GenAI SDK for Java, with environments, templates, and snapshots submodules. (7dc24fb)
• Add enable_data_retention to ToolParallelAiSearch, Add step_count to ReinforcementTuningHyperParameters, Add BidiGenerateContentSetup (3bb6b4c)
• Add sandbox templates and snapshots submodules to the Vertex AI GenAI SDK for Java. (73bd43f)
• Add sandboxes.pause() and sandboxes.resume() methods to the Agent Engine sandbox SDK across Python, Java, and JS SDKs. (d8ad68e)
• Add Shell Sandbox environment support to the Agent Engine sandbox SDK (8639493)
• agentplatform: Support client.memory_banks.get (c6af60d)
• agentplatform: Support client.memory_banks.list (c6af60d)
• agentplatform: Support Memory Bank configs. (c6af60d)
• Allow setting ingress_control_config when creating a SandboxEnvironmentTemplate via the SDK (Python, Java, JS). (1e95097)
• Expose ingress_control_config field on SandboxEnvironmentTemplate across Python, Java, and JS SDKs. (4507f78)
• Expose SandboxEnvironmentTemplateState as a standalone enum class in the Python, Java, and JS SDKs. (2eb6999)
• Expose service_attachment field on SandboxEnvironmentConnectionInfo across Python, Java, JS, and Go SDKs. (adb993b)
• Expose STATE_PAUSED, STATE_PAUSING, and STATE_RESUMING values in the SandboxState enum for SandboxEnvironment across Python, Java, and JS SDKs. (b5d9819)

Bug Fixes

• Update generator configuration and SDK bindings for Agent Engine Session update calls to return Session directly. (037692b)

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