feat(core): implement Runner.runLive and LlmAgent live flow

[tSte]

Implements the bidirectional (live) orchestration that was left as a TODO after #409 (which added only the GeminiLlmConnection layer): runner.ts carried // TODO b/425992518: Implement runLive and LlmAgent.runLiveFlow threw not implemented.

• Runner.runLive: opens the invocation, runs the before/on-event/after-run plugin hooks, drives agent.runLive, and persists events while skipping raw inline-audio blobs (shouldAppendLiveEvent).
• LlmAgent.runLiveFlow: preprocess (same processors as runAsync) -> connect ->
  parallel send loop + receive loop -> tool execution -> sub-agent transfer. Reconnects transparently on goAway / recoverable drops when a session resumption handle is available, skipping history replay on resume.
• InvocationContext.liveRequestQueue / liveSessionResumptionHandle.
• LiveRequestQueue.get(abortSignal) to release a parked read on teardown.
• RunConfig.contextWindowCompression, forwarded to the live connect config.
• Gemini.connect: model-version-aware live API version routing and stripping of the Vertex-only sessionResumption.transparent flag on the AI Studio backend.

Adds core/test/runner/run_live_test.ts (16 tests covering realtime/audio, transcription persistence, tool calls, resumption capture, goAway reconnect, externally supplied handles, activity signals, sub-agent transfer) and liveApiVersion / transparent-strip coverage in google_llm_test.ts.

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