Add version flags to parakeet-cli and parakeet-server

[quartzjer]

Fixes #36.

Adds --version / -V to both installed executables:

• parakeet-cli --version
• parakeet-cli -V
• parakeet-server --version
• parakeet-server -V

The version string comes from a new PARAKEET_VERSION CMake cache setting, with the existing 0.0.1 fallback preserved for builds that do not pass a value. Release builds now pass the tag-derived semantic version into CMake, while keeping existing release artifact names unchanged.

Validation:

• Configured with -DPARAKEET_VERSION=9.8.7
• Built successfully
• Ran ctest --test-dir build-codex-version --output-on-failure -LE model
• Verified both binaries print 9.8.7 for --version and -V