Fixes: #3348

Problem:
On Windows 11 with SMB-mounted network drives, Path.resolve() can return a
\\?\Volume{GUID}\... form that Windows cannot open via a plain string.
read_config() called .resolve() to compute curr_dir and immediately wrote
that back into config.yaml and returned it in cfg["project_path"].
All downstream code that builds paths from project_path using str() or
string concatenation then failed with FileNotFoundError.

The PyTorch engine was mostly unaffected because it keeps Path objects in
memory; the TensorFlow engine was broken because predict_videos.py converts
paths to strings before passing them to load_config().

Summary:
This PR addresses the problem in 2 ways:
1 Replace Path(..).resolve() with Path(..).absolute(). The purpose of this line is only to
detect when a project has been moved — symlink resolution is unnecessary, and
.absolute() is safe across all platforms and mount types.
2. Add a helper safe_resolve(path: Path) → Path for safe path resolution for when the resolved path
cannot be opened as a string. This can be used wherever symlink resolution is
genuinely useful (e.g. image/data paths).

Changes:

• In read_config(), replaced Path(configname).parent.resolve() with
  Path(configname).parent.absolute(). to fix read_config() project path resolution can break path #3348
• Follow the same pattern in create_project/new.py, create_project/new_3d.py, gui/tabs/analyze_videos.py
• In generate_training_dataset/frame_extraction.py, removed a redundant .resolve() on the config path before passing it to
  read_config() — the fix in read_config() makes this unnecessary.
• Add a helper in auxiliaryfunctions.py: safe_resolve(path: Path) → Path
• in pose_estimation_pytorch/modelzoo/memory_replay.py, replaced .resolve() calls on image/data paths with safe_resolve(), so symlinks are still followed where possible while remaining safe on Win11 SMB.

Tests:

Added TestSafeResolve and TestReadConfigProjectPath in
tests/test_auxiliaryfunctions.py:

• Verifies safe_resolve() returns the resolved path on normal filesystems.
• Verifies safe_resolve() falls back to .absolute() when resolve() is
  unusable.
• Verifies read_config() replaces a persisted \\?\Volume{GUID}\... path
  with a usable directory.
• Verifies read_config() still auto-updates project_path when a project is
  moved to a new location (the original feature this logic implements).

Notes:

• We currenly use str paths and pathlib.Path mixed throughout the codebase. We should settle for pathlib.Path everywhere (up to 3rd party boundaries that require str). This requires a bigger refactor, so will be addressed in a separate PR. pathlib.Path is better at handling edge cases like server paths, preventing issues like read_config() project path resolution can break path #3348. Also, we can fix brittle cases where paths are joined manually parent + "/" + file, and make the codebase use more uniform function signatures.
• The fact that read_config() currently also writes to the config is not very convenient or intuitive. It will be better to keep separate read and sync of the config files. This is addressed in [WIP] Final migration to configuration version 1: structured and validated configs #3198