Regex filter never matches blank text under the default ByWordAny: IsMatch(" ", @"\s", Regex) and IsMatch("", "^$", Regex) return false #193

What's wrong

Under the default TextFilterMatchOptions.ByWordAny, a regex filter can't match text that is empty or only whitespace, even when the pattern is written to match exactly that:

So a "find the blank entries" filter such as ^\s*$ or \s+ misses exactly the entries it is looking for, but only under the default option. The same pattern does match whitespace when the text also contains a word.

I checked this with a scratch MSTest against main at 5f420d9.

Cause

In DoesMatchRegex (TextFilter/TextFilter.cs:735-746), the early return for blank text comes before the ByWordAny whole-text attempt:

if (textTokens.Count == 0)
{
    return false;          // added for #107/#109 so ByWordAll isn't vacuously true
}

if (textFilterMatchOptions is TextFilterMatchOptions.ByWordAny && IsMatchWithinTimeout(ref activeRegex, cacheKey, text))
{
    return true;           // added for #125: patterns that span whitespace match the whole text
}

Blank text splits into zero words, so the function returns before the whole text is ever matched. The early return was only needed for ByWordAll, where Enumerable.All over an empty set is vacuously true.

Suggested fix

Move the ByWordAny whole-text check above the textTokens.Count == 0 return, or limit that return to ByWordAll. Either way, #107/#109 stays fixed: under ByWordAll, blank text still matches nothing.

Acceptance criteria

• IsMatch(" ", @"\s", Regex) and IsMatch("", "^$", Regex) return true under ByWordAny
• Under ByWordAll, blank text still matches no pattern (the Regex + ByWordAll matches empty or whitespace-only text against any pattern #107/Stop regex ByWordAll matching blank text #109 tests still pass)
• Tests cover blank and whitespace-only text under both options