Pilot for the SessionOrchestrator god-class decomposition. Moves executeStage
(426-line stage-execution driver) out to SessionOrchestratorExecution.kt as an
internal extension fun, hoists three nested holders (RunEffectives,
ArtifactLadderOutcome, RenderedToolResult) to top-level in
SessionOrchestratorTypes.kt, and promotes class/protected members to internal so
extensions can reach them. Behavior-preserving relocation; kernel+test+server
compile green.
kami
7f820bafe6