perf(pet-windows-registry): parallelize HKLM/HKCU walk and reuse cache across refresh #1516

Job	Run time
Tests (windows-latest, x86_64-pc-windows-msvc, yes)	8m 13s
Builds (windows-latest, x86_64-pc-windows-msvc)	5m 34s
Tests in Containers (ci-homebrew-container, ubuntu-latest, homebrew/brew, x86_64-unknown-linux-musl)	3m 55s
Builds (macos-latest, x86_64-apple-darwin, yes)	3m 40s
Tests (macos-latest, x86_64-apple-darwin, yes)	16m 38s
Tests in Containers (ci-jupyter-container, ubuntu-latest, mcr.microsoft.com/devcontainers/univers...	4m 41s
Tests (ubuntu-latest, x86_64-unknown-linux-musl, yes)	9m 35s
Env Tests (ci-poetry-global, ubuntu-latest, x86_64-unknown-linux-musl)	2m 41s
Builds (macos-14, aarch64-apple-darwin, yes)	3m 37s
Env Tests (ci-poetry-project, ubuntu-latest, x86_64-unknown-linux-musl)	3m 8s
Builds (windows-latest, aarch64-pc-windows-msvc)	5m 23s
Tests (macos-14, aarch64-apple-darwin, yes)	12m 44s
Builds (ubuntu-latest, x86_64-unknown-linux-musl, yes)	2m 25s
Env Tests (ci-poetry-custom, ubuntu-latest, x86_64-unknown-linux-musl)	3m 6s
Env Tests (ci-poetry-global, windows-latest, x86_64-pc-windows-msvc)	5m 27s
Env Tests (ci-poetry-project, windows-latest, x86_64-pc-windows-msvc)	7m 18s
Env Tests (ci-poetry-custom, windows-latest, x86_64-pc-windows-msvc)	5m 51s
	1h 43m 56s

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