Under a deep root, the cache entry
<root>/graphify-out/cache/ast/v<ver>-s<schema>-g<grammars>/<64 hex>.json,
and mkstemp's even longer <hash>.<random>.tmp temp name, overrun Windows
MAX_PATH. save_cached raised FileNotFoundError and `graphify extract`
failed with "AST extraction failed" (e.g. any project under the default
%TEMP% of a long user name).
Move detect._os_path (the \?\ helper from #1655) to paths.os_long_path
so cache.py can share it, and use it for the entry and temp file in
save_cached and load_cached. detect._os_path stays as an alias. Keys are
unaffected: _normalize_path still strips the prefix.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
(cherry picked from commit abf9c9f6ab)
