Replace galette-agent PathUtils with minimal jlink-safe version

The 606-line PathUtils with System.out.println in static initializer,
Runtime.addShutdownHook, HashSet, and Tag dependencies was a WIP from
commit ba5cc95 ("working on integrating, does not work yet"). It breaks
the jlink image because its static initializer triggers class loading
of String/Thread during JDK instrumentation.

Replaced with a minimal version containing only:
- Instrumented comparison stubs (instrumentedIcmpJump, instrumentedDcmpl, etc.)
- Thread-local constraint storage with recursion guard
- flush()/getCurrent()/reset() for GalettePathConstraintBridge access
- No static initializer side effects (no System.out, no shutdown hooks)

Note: jlink image still fails with AbstractMethodError on String.equals.
This appears to be a pre-existing issue with the Patcher/jlink pipeline
in this devcontainer environment, unrelated to PathUtils content.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: AnneKoziolek