Fuzzy filter treats inner whitespace as a literal character: "open file" can't find OpenFile.cs, and a double space or tab hides everything #142

What's wrong

The fuzzy path passes the filter to Fuzzy.Contains after trimming only the ends (TextFilter/TextFilter.cs:251: Fuzzy.Contains(text.AsSpan(), filter.AsSpan().Trim(), out score)). Whitespace inside the query is a character the text must contain, unlike Glob and Regex, where whitespace separates tokens.

Repro (main @ 6ce4850)

string[] items = { "OpenFile.cs", "open_file.cs", "SaveFile.cs", "open file dialog" };
TextFilter.Filter(items, "open file",  TextFilterType.Fuzzy);   // [open file dialog]
TextFilter.Filter(items, "open  file", TextFilterType.Fuzzy);   // []   (two spaces)
TextFilter.IsMatch("OpenFile",     "open file",  TextFilterType.Fuzzy);  // false
TextFilter.IsMatch("open_file.cs", "open file",  TextFilterType.Fuzzy);  // false
TextFilter.IsMatch("OpenFile",     "openfile",   TextFilterType.Fuzzy);  // true
TextFilter.IsMatch("open file",    "open\tfile", TextFilterType.Fuzzy);  // false

Expected: a word break in a fuzzy query still finds OpenFile.cs and open_file.cs (as openfile already does), and an extra space or a tab doesn't empty the list.

Why it matters

#115 trimmed leading/trailing padding on the grounds that padding shouldn't become a space the text must contain; inner spaces have the same problem. A natural two-word query, or an accidental double space, silently hides real matches, and fuzzy behaves differently from the other two filter types.

Suggested fix

Either:

• (a) Strip all whitespace from the fuzzy filter before calling Fuzzy.Contains (smallest change), or
• (b) Split on whitespace, require every piece to fuzzy-match, and sum the scores. This would also give TextFilterMatchOptions a meaning for fuzzy, which it currently ignores.

Acceptance: the repro's "open file", "open file" and "open\tfile" queries match OpenFile.cs, open_file.cs and open file dialog, and not SaveFile.cs.