9.2.0

Added

• Export-PhaseTimingTree - the export counterpart of the 2-level
  Write-PhaseTimingReport compat shim. Serialises the module-private default
  context ($script:DefaultPhaseTimingTree, the tree the phase/sub-step shims
  build) to the versioned nested-JSON schema (e2e-timing/v1) by delegating to
  the context-explicit core Export-TimingSpanTree. Same no--Tree surface and
  same "return silently when the context was never initialised" null-guard as
  Write-PhaseTimingReport, so it is safe to call from the same outer finally.
  Gives a shim consumer (provision.ps1, register-runners.ps1) the missing
  handle to serialise its timings for the cross-process handoff, on the
  TIMING_TREE_OUTPUT_PATH opt-in, without exposing the default context or
  overloading the core verb with a hidden-global fallback.