* feat(discord): auto-join occupied voice rooms
Add opt-in voice.autoJoin[].whenOccupied residency so Discord voice bots join for the first human and leave when the room becomes empty while preserving existing always-on, manual, transcript, and follow-user behavior.\n\nCloses #125973
* test(discord): isolate process runtime mocks
Use stable hoisted runtime-env mocks so isolate=false Discord test ordering cannot turn sleepWithAbort back into an unmocked function.
* fix(discord): defer unknown voice occupancy
Treat memberless voice states as unresolved instead of human so bot-only rooms cannot trigger occupancy-managed auto-join. Add cache-to-listener and manager regressions.\n\nCloses #125973
* test: isolate shared module mocks
Replace ineffective non-isolated module spies with stable hoisted mocks and a child-process SQLite connection-reuse probe so gateway and Discord shards are order-independent.
* test(gateway): inline connection reuse probe
Keep the child-process SQLite ownership probe in its owning Vitest file so Knip sees the full test surface without weakening process isolation or the original order regression.
Peter Steinberger
554dfbe0a2