* fix(utils): tolerate bavail greater than bfree on Linux
Treat f_bavail > f_bfree as a compatibility edge case instead of fatal corruption during startup disk info probing.
- keep corruption checks for other invalid counter relationships
- log a warning and clamp reserved blocks to 0 when bavail exceeds bfree
- add linux unit coverage for the compatibility and overflow paths
Refs #3025
* fix(utils): cap bavail to bfree for Linux statfs edge
* fix(utils): rate-limit Linux statfs compatibility warning
* test(utils): cover Linux statfs capacity math
Expand Linux statfs capacity math tests around normal, equal, zero, and fully-free block counter combinations.
Refs #3025
* fix(utils): avoid statfs warning guard reallocations
* test(utils): align statfs reserved block expectations
* fmt
* fix(utils): avoid warning guard path allocation
Check the warn-once set before allocating a PathBuf so repeated bavail/bfree compatibility warnings stay low-overhead.
Refs #3025
