perf(pet-windows-registry): parallelize HKLM/HKCU walk and reuse cache across refresh #1519

Job	Run time
Tests in Containers (ci-homebrew-container, ubuntu-latest, homebrew/brew, x86_64-unknown-linux-musl)	3m 54s
Tests in Containers (ci-jupyter-container, ubuntu-latest, mcr.microsoft.com/devcontainers/univers...	4m 46s
Tests (windows-latest, x86_64-pc-windows-msvc, yes)	8m 32s
Tests (ubuntu-latest, x86_64-unknown-linux-musl, yes)	9m 45s
Builds (windows-latest, aarch64-pc-windows-msvc)	5m 9s
Builds (macos-14, aarch64-apple-darwin, yes)	2m 32s
Builds (ubuntu-latest, x86_64-unknown-linux-musl, yes)	2m 28s
Env Tests (ci-poetry-project, windows-latest, x86_64-pc-windows-msvc)	6m 7s
Env Tests (ci-poetry-project, ubuntu-latest, x86_64-unknown-linux-musl)	3m 4s
Env Tests (ci-poetry-global, windows-latest, x86_64-pc-windows-msvc)	8m 20s
Tests (macos-14, aarch64-apple-darwin, yes)	12m 22s
Builds (windows-latest, x86_64-pc-windows-msvc)	5m 8s
Env Tests (ci-poetry-custom, windows-latest, x86_64-pc-windows-msvc)	1m 2s
Tests (macos-latest, x86_64-apple-darwin, yes)	13m 7s
Env Tests (ci-poetry-custom, ubuntu-latest, x86_64-unknown-linux-musl)	2m 54s
Env Tests (ci-poetry-global, ubuntu-latest, x86_64-unknown-linux-musl)	3m 8s
Builds (macos-latest, x86_64-apple-darwin, yes)	2m 26s
	1h 34m 44s

Provide feedback