Remove 256-character limit on document matching criteria

Description Currently, the match field in MatchingModel is limited to 256 characters. While sufficient for simple keyword matching, this creates a significant limitation for advanced document automation. When using Regular Expressions (RegEx) or the "Any word" matching algorithm, users often need to include long strings of alternative terms, complex lookaheads, or extensive lists of identifiers. Once the 256-character limit is reached, it is impossible to save the criteria, forcing users to create multiple identical tags/correspondents to cover a single logical category. Proposed Solution 1. Backend Change: Modify the match field in src/documents/models.py from a CharField to a TextField. This removes the hardcoded 256-character limit while maintaining backward compatibility. 2. Frontend Change: Update the UI to use a textarea instead of a single-line input field. This provides better visibility for long RegEx patterns or large word lists. Impact ̶…