🛡️ Sentinel: Fix SIGBUS crash on hard-linked output files

[kassoulet]

🛡️ Sentinel: [CRITICAL] Fix SIGBUS crash on hard-linked output files

🚨 Severity: CRITICAL
💡 Vulnerability: Application crash (SIGBUS) when output file is a hard link to input file.
🎯 Impact: Denial of service or application failure when processing bzip2 files. Truncating a memory-mapped file triggers a Bus error.
🔧 Fix: Enhanced the file identity check to compare device and inode numbers on Unix systems.
✅ Verification: Ran a reproduction script (test_hardlink.sh) which previously caused a SIGBUS and now results in a clean error message.

ln input.bz2 output.bz2
bz2zstd input.bz2 -o output.bz2
# Before: Bus error (SIGBUS)
# After: Error: Input and output files must be different: "output.bz2"

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PR created automatically by Jules for task 10380662204608335638 started by @kassoulet

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