perf(pet-windows-registry): parallelize HKLM/HKCU walk and reuse cache across refresh #1521

Job	Run time
Tests in Containers (ci-jupyter-container, ubuntu-latest, mcr.microsoft.com/devcontainers/univers...	4m 51s
Builds (windows-latest, x86_64-pc-windows-msvc)	7m 21s
Env Tests (ci-poetry-global, ubuntu-latest, x86_64-unknown-linux-musl)	3m 20s
Tests (ubuntu-latest, x86_64-unknown-linux-musl, yes)	9m 43s
Tests (macos-14, aarch64-apple-darwin, yes)	11m 26s
Tests (windows-latest, x86_64-pc-windows-msvc, yes)	7m 49s
Builds (macos-latest, x86_64-apple-darwin, yes)	3m 42s
Builds (ubuntu-latest, x86_64-unknown-linux-musl, yes)	2m 21s
Env Tests (ci-poetry-project, windows-latest, x86_64-pc-windows-msvc)	8m 38s
Env Tests (ci-poetry-custom, ubuntu-latest, x86_64-unknown-linux-musl)	3m 5s
Tests (macos-latest, x86_64-apple-darwin, yes)	13m 23s
Builds (macos-14, aarch64-apple-darwin, yes)	2m 45s
Env Tests (ci-poetry-custom, windows-latest, x86_64-pc-windows-msvc)	6m 17s
Env Tests (ci-poetry-global, windows-latest, x86_64-pc-windows-msvc)	6m 30s
Tests in Containers (ci-homebrew-container, ubuntu-latest, homebrew/brew, x86_64-unknown-linux-musl)	3m 59s
Env Tests (ci-poetry-project, ubuntu-latest, x86_64-unknown-linux-musl)	2m 53s
Builds (windows-latest, aarch64-pc-windows-msvc)	6m 32s
	1h 44m 35s

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