perf(pet-windows-registry): parallelize HKLM/HKCU walk and reuse cache across refresh #1517

Job	Run time
Tests in Containers (ci-homebrew-container, ubuntu-latest, homebrew/brew, x86_64-unknown-linux-musl)	3m 52s
Tests in Containers (ci-jupyter-container, ubuntu-latest, mcr.microsoft.com/devcontainers/univers...	4m 47s
Tests (macos-14, aarch64-apple-darwin, yes)	10m 48s
Builds (macos-latest, x86_64-apple-darwin, yes)	3m 19s
Tests (windows-latest, x86_64-pc-windows-msvc, yes)	8m 28s
Builds (ubuntu-latest, x86_64-unknown-linux-musl, yes)	2m 21s
Tests (ubuntu-latest, x86_64-unknown-linux-musl, yes)	9m 17s
Tests (macos-latest, x86_64-apple-darwin, yes)	15m 46s
Env Tests (ci-poetry-project, windows-latest, x86_64-pc-windows-msvc)	5m 54s
Builds (macos-14, aarch64-apple-darwin, yes)	2m 14s
Env Tests (ci-poetry-custom, windows-latest, x86_64-pc-windows-msvc)	6m 12s
Env Tests (ci-poetry-global, windows-latest, x86_64-pc-windows-msvc)	6m 59s
Env Tests (ci-poetry-project, ubuntu-latest, x86_64-unknown-linux-musl)	2m 47s
Env Tests (ci-poetry-custom, ubuntu-latest, x86_64-unknown-linux-musl)	2m 53s
Env Tests (ci-poetry-global, ubuntu-latest, x86_64-unknown-linux-musl)	3m 6s
Builds (windows-latest, aarch64-pc-windows-msvc)	6m 0s
Builds (windows-latest, x86_64-pc-windows-msvc)	5m 14s
	1h 39m 57s

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