- Add XOR_KEY constant matching FORMAT.md Section 9.1
- Add xorHeader() function with signed byte masking (and 0xFF)
- Update decode() with XOR bootstrapping: check magic, XOR if mismatch
- Update decode() with TOC decryption: decrypt when flags bit 1 is set
- Backward compatible: plain headers and unencrypted TOC still work
- Checks prerequisites (kotlinc, java, cargo) with install instructions
- Test 1: single text file round-trip (Rust pack -> Kotlin decode)
- Test 2: multiple files with mixed content (text + 10KB binary)
- Test 3: no-compress mode for pre-compressed files
- Test 4: empty file edge case
- Test 5: large file (100 KB random data)
- SHA-256 comparison of original vs extracted for each test
- Colored output, temp directory cleanup via trap, non-zero exit on failure
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
