Fix incorrect singularization for words ending with -ves (arrives/drives/curves/behaves) and add tests

[jesi318]

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Summary

Fixes a bug where arrives.Singularize() → arrife (and similar: drives → drife, curves → curf, behaves → behafe etc) by adjusting the singularization rule set and ordering.
Adds unit tests that assert correct singular forms for common -ves cases and true -fe exceptions.

• fixes Humanizer Core - Singular of "arrives" is "arrife" #1674

Why this change was made/ Root Cause
_default.AddSingular("([^f])ves$", "$1fe"); is a greedy rule which matched other strings mentioned in the issue above

What I changed

Reworked -ves singular rules in Vocabularies.Defaultso exceptions for nouns that map to -f/-fe (knife→knives, wife→wives, leaf→leaves, etc.) are handled before the general catch-all that converts -ves → -ve (verbs/adjectives like arrive/drive/curve/behave).
Replaced overly-generic pattern(s) that caused verbs to be mis-singularized with a combination of:

• Explicit stem-based rules for known -f/-fe nouns, and

• A general (.+)ves$ -> $1ve catch-all for remaining -ves cases.

• Corrected the incorrect test yield return ["safe", "saves"]; to yield return ["safe", "safes"]; (which makes it grammattically correct according to me) and added a rule for it since it was an edge case . Please let me know if I'm wrong.

• Added a focused unit test method Singularize_Ves_EdgeCases in InflectorTests.cs

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve -rves nouns when singularizing

The new allow-list in the -ves -> -f singular rule is now narrower than the existing plural rule, which creates a regression for words ending in -rf/-lf that are not enumerated here. For example, "scarf".Pluralize() still becomes "scarves" via (?:([^f])fe|([lr])f)$, but "scarves".Singularize() now misses this rule and falls through to (.+)ves$ -> $1ve, returning "scarve". This breaks round-tripping for valid inflections and should be fixed by restoring generic coverage (or adding the missing stems) in the singular rules.

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