feat: add historyConfig support for live connection initial context history seeding

[jadfeitrouni]

Summary

• Adds HistoryConfig interface with initialHistoryInClientContent option to support seeding initial conversation context via sendClientContent before starting a realtime session
• Wires up historyConfig in liveConnectConfigToMldev, liveClientSetupToMldev, and the token converters
• Adds unit test coverage for the Gemini API path
• Adds sdk-samples/live_history_config.ts example demonstrating the feature

Context

The gemini-3.1-flash-live-preview model does not allow sendClientContent during a session unless initial_history_in_client_content is set in the session config. This option is already supported in the Python SDK but was missing from the JS/TS SDK.

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