Some PM code reaches a store root from paths.store_root() or
writable_store_root() directly instead of through Store, so its file
calls kept the ordinary spelling and stay cut at MAX_PATH on Windows
with LongPathsEnabled=0. Worse, its comparisons against a Store root
(now \\?\-spelled) never matched.
Each such root now gets long_root() once, where the variable is born:
- Facts.refresh_digests digests whole payload tool trees;
- verified_tools walks and digests the source store's tool trees;
- the uv cache seed copies the payload's deep uv-cache tree out;
- _toolchain's writable store, so `location.root != writable` compares
like with like and the copy store is built from the same spelling;
- _installed_location passes store.root to Facts.installed;
- ensure() picks the shipped facts by comparing two Store roots;
- the corrupt-facts guard compares both sides spelled long.
Returned and exported paths stay ordinary (previous commit).
1f817761dc