* feat(voice): unify Live sessions across calls and meetings
Resolve provider capabilities and interruption policy through the shared realtime voice owner. Keep meeting input isolated from virtual-microphone output, reuse native delegation for meetings and Voice Call, and preserve explicit Stop across browser and Apple relay clients.\n\nValidated with real Live API and synthetic Chromium/WebRTC proof, focused regressions, changed-file checks, and independent review. Related to #146289.
* test(voice): align capture fixtures and validation gates
Model browser audio capture in the shared meeting RPC fixtures so startup
failure tests reach the provider and verify capture cleanup. Preserve the
same relay startup behavior while simplifying duplicate lifecycle branches.
Rebalance the pre-existing 702-root platform test graph by moving security
tests beside sandbox/tool tests; keep coverage, graph counts, and limits.
* fix(meetings): preserve configured input commands
Keep explicitly configured capture/filter/mixer output as provider input on
local Chrome and paired nodes, preserving the v2026.9.4 contract. Generated
input and output-only overrides continue to use managed browser capture.
Retain Live's isolation guard and explain how to remove an input override
when selecting Live. Prove the actual PCM paths through both meeting engines
and transports, and document the preserved configuration behavior.