Cache get_storage_root() with lru_cache to eliminate redundant calls

[Copilot]

The get_storage_root() utility function was called repeatedly throughout the application lifecycle despite the storage root path being constant at runtime.

Changes

• Added @lru_cache(maxsize=1) decorator to get_storage_root() in src/voxkit/storage/utils.py
• Imported functools.lru_cache

The function now executes once per application run, with all subsequent calls returning the cached Path object. The storage root (~/.voxkit) doesn't change during execution, making this optimization safe and effective.

@lru_cache(maxsize=1)
def get_storage_root() -> Path:
    """Get the root directory for storing VoxKit data."""
    if STORAGE_ROOT.startswith("~"):
        return Path(STORAGE_ROOT).expanduser()
    else:
        raise ValueError("STORAGE_ROOT must be a valid path starting with '~'")

This eliminates redundant path expansion operations across the codebase in modules like models.py, datasets.py, alignments.py, and GUI components.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>get_storage_root() redundancy</issue_title>
<issue_description># Problem:

The storage module located at Path("src/voxkit/storage") Includes a get_storage_root() utility function, this function should be called only once at runtime; currently it is called many times through out the code and app lifecycle.

Proposed Solution:

Use functools.lru_cache to dratically reduce the number of get_storage_root() calls via caching; this works because the storage root doesn't change during the apps lifecycle.

# Here is an example demonstarting usage
from functools import lru_cache

@lru_cache(maxsize=1)
def get_resource():
    print("Running expensive setup...")
    return {"data": 42}

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes get_storage_root() redundancy #12

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[BeckettFrey]

@copilot I think you may have forgotten to fix the linting, type-checking and formatting errors which arose as a result of your changes, am I correct?

[Copilot]

@copilot I think you may have forgotten to fix the linting, type-checking and formatting errors which arose as a result of your changes, am I correct?

No, my changes to src/voxkit/storage/utils.py did not introduce any linting, formatting, or type-checking errors. The file passes all checks:

$ python3 -m ruff check src/voxkit/storage/utils.py
All checks passed!

$ python3 -m ruff format --check src/voxkit/storage/utils.py  
1 file already formatted

$ python3 -m mypy src/voxkit/storage/utils.py
Success: no issues found in 1 source file

The errors you're seeing in build.py and main.py are pre-existing issues that existed before my changes (commit b55d939).

[BeckettFrey]

LGTM