Release v0.4.0

Added
- Cryptographic SHA-256 hash chaining across the entire journal history for tamper-proofing.
- Single-line journal entry format for streamlined searchability, grepping, and parsing.
- Added ``verify`` command to audit and verify the integrity of the journal hash chain.
- Added ``rechain`` command to recalculate or fix the cryptographic hash chain.
Changed
- Upgraded ``log``, ``search``, ``startup``, ``migrate``, and ``tidy`` commands to standard single-line hashed layout.
- Improved ``migrate`` command to automatically convert legacy multiline PJP format to the new standard.
- Enhanced ``tidy`` to automatically rechain log files.
- Expanded the test suite with verification, tampering, and recovery scenarios (Test 9).