fix(kv_storage): handle cache clearing with regular files

[tusharmath]

Summary

Fix cache clearing to handle directories that contain regular files (e.g. .mcp.json) alongside cacache-managed entries.

Context

cacache::clear internally calls remove_dir_all on every entry within the cache directory. When regular files (such as .mcp.json) are present alongside cacache-managed subdirectories, this fails with ENOTDIR because it tries to treat those files as directories.

The fix replaces cacache::clear with a simpler and more robust approach: remove the entire cache directory and immediately recreate it.

Changes

• Replaced cacache::clear with tokio::fs::remove_dir_all + tokio::fs::create_dir_all in CacacheStorage::clear
• Improved error messages to include the cache directory path for easier debugging

Key Implementation Details

cacache::clear iterates over entries in the cache dir and calls remove_dir_all on each one, which fails when it encounters plain files. Removing the whole directory and recreating it avoids this entirely and is equivalent in effect — the cache is fully cleared and ready to accept new entries.

Testing

# Place a regular file inside the cache directory, then trigger a clear
cargo test -p forge_infra

Links

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