Parity: Find and Replace special characters and wildcards (^p, ^t, ^?, ^#, Use wildcards) #543

Find and Replace treats ^p, ^t etc. literally. Word's Find/Replace supports special codes and a wildcard mode.

Plan:

• Special codes in Find and Replace (Special ▾ menu in the dialog): paragraph mark ^p, tab ^t, any character ^?, any digit ^#, any letter ^$, caret ^^, manual line break ^l, manual page break ^m, section break ^b, column break ^n, em/en dash ^+ / ^=, nonbreaking space ^s, nonbreaking hyphen ^~, optional hyphen ^-, white space ^w, "Find what text" ^& (in Replace), clipboard contents ^c (Replace).
• "Use wildcards" mode: ?, *, [abc], [a-z], [!x], {n,m}, @, <, >, ( ) groups and \1 back-references in Replace.
• Match case / whole words / prefix / suffix / ignore punctuation / ignore white-space options where not yet there.
• Engine: edit.find / edit.replace params (special, wildcards, …) so agents get the same; Replace with ^p splits paragraphs.
• Tests per code family and wildcard grouping/back-references; hostile patterns bounded (no catastrophic backtracking).

I'm working on this (vangel76); PR follows.