sugar_path-v3.0.0

Breaking redesign of the public path APIs for borrowing, explicit cwd, and owned-buffer reuse (#40). Public docs and continuous CI allocation gates were aligned with that surface (#42). Performance baselines landed first as PR #41.

Added

• Add try_absolutize and try_relative for callers that handle ambient current-directory errors.
• Add relative_with for relative calculation against an explicit externally managed cwd.
• Add strict, fallible strict, and explicitly lossy slash conversion for borrowed paths and consuming PathBuf values.
• Add consuming PathBuf normalization through the sealed SugarPathBuf extension trait.

Changed

• Seal SugarPath as an extension-method namespace implemented directly for Path and str; owned standard types and string wrappers continue to use it through deref method lookup.
• Change relative to return Cow<Path> directly, borrowing a canonical descendant suffix when possible; callers requiring PathBuf use Cow::into_owned.
• Follow Node-style host-native normalization by preserving one trailing separator on non-root paths and preserving Windows drive-letter spelling while retaining case-insensitive drive comparison.
• Keep relative output independent from normalization's trailing-separator preservation: equal paths return an empty path and target trailing separators are removed.
• Change to_slash to the ergonomic strict conversion that panics for invalid Unicode, and move the non-replacing fallible contract to try_to_slash.
• Change absolutize_with and relative_with to accept borrowed or owned cwd values directly without requiring callers to construct Cow; an owned PathBuf may transfer its allocation.
• Preserve full non-UTF-8 Path and OsStr behavior for path operations; only conversion to Unicode chooses strict, fallible, or lossy policy.

Fixed

• Preserve complete drive, UNC, verbatim UNC, and device roots when calculating Windows relative paths, including invalid-wide fallback inputs.
• Preserve unresolved Windows drive-relative paths when an explicit cwd belongs to another drive instead of consulting ambient state or fabricating a rooted path.
• Preserve literal / characters inside Windows verbatim components, keep or insert the minimal .\ needed to prevent a normal component from becoming a prefix during normalization, and return the normalized target when a component cannot be represented as a standalone native relative path.

Performance

• Avoid current-directory access for inputs whose result is cwd-independent.
• Avoid result allocation for canonical native descendant relative calls on Unix and Windows.
• Reuse owned cwd, normalized PathBuf, and valid-Unicode slash-conversion buffers where possible.
• Use separator-aware Windows comparisons, inline component storage, memchr, and target-specific common-prefix scanning for Rolldown-shaped paths.

Migration

• Append .into_owned() to relative(base) only where the former owned PathBuf result is still required.
• For known-UTF-8 owned text, replace relative(base).to_slash_lossy().into_owned() with relative(base).into_owned().into_slash(); otherwise select the strict fallible or explicitly lossy conversion that matches the caller's encoding policy.
• Replace to_slash().unwrap() with to_slash() when valid UTF-8 is an invariant, and use try_to_slash() when invalid encoding is recoverable.
• Pass cwd directly to absolutize_with and relative_with; do not wrap it in Cow::Borrowed or Cow::Owned.