## Why
Read-deny policies must use the target executor's path convention so URI-based
policy checks and native filesystem enumeration enforce the same rules.
## What changed
- Prepare deny roots and glob matchers from `PathUri` policy context, including
executor-relative working directories and home-relative patterns.
- Match Windows globs case-insensitively with normalized separators, while
preserving byte-oriented POSIX matching for non-UTF-8 paths.
- Fail closed for malformed paths, incompatible path conventions, unresolved
home-relative patterns, and invalid globs.
- Make Windows deny-read discovery use case-insensitive ripgrep glob matching.
## Testing
Added coverage for Windows URI conventions, executor home expansion,
case-insensitive `.env` discovery, malformed paths, non-UTF-8 names, and
canonical directory-link targets.
GitOrigin-RevId: 36001219a2e9b36acfce8972dc1d3bbc304271c5