Agent spawn telemetry now records request shape, non-interactive flag, and workflow phase

What

• Agent/task spawn telemetry now includes optional workflowPhase, requestShape, and requestNonInteractive fields when present.
• A new helper computes {requestShape, requestNonInteractive} for each subagent launch: requestShape is 'foreground' or 'background' depending on how the subagent was launched, and requestNonInteractive is a boolean. These are captured at subagent launch time, propagated through to teardown, and merged into telemetry-adjacent objects in several places, including worktree teardown and subagent tool launch options.
• Relatedly, another new helper scans queued messages for a SubagentStart hook's additional context and for skill-loading metadata (isSkillLoadingMetadata), computing hookContextCarried and carriedPreloads so hook context and preloaded skill state carry across resumed, skill-loaded turns.

Why This gives more detail in telemetry about how and why subagents are launched (foreground vs. background, interactive vs. not, and at what point in a workflow), and ensures hook context and skill preloads aren't lost when a subagent's turn is resumed after loading a skill.