[ENHANCEMENT] Add support for more header/footer patterns

[kiku-jw]

Description

Currently, DocStripper removes common header/footer patterns, but there are many more patterns used in documents that could be detected and removed.

Use Case

Users working with documents from different sources encounter various header/footer formats that aren't currently detected.

Proposed Solution

Expand the pattern matching in DocStripper class to support:

• More language variations (French, German, Chinese, etc.)
• Date-based headers/footers
• Custom pattern matching
• User-defined patterns (future enhancement)

Files to Modify

• docs/assets/app.js - DocStripper class
• tool.py - Python CLI version

Examples of Patterns to Add

• Seite X von Y (German)
• Page X sur Y (French)
• 第 X 页，共 Y 页 (Chinese)
• Date patterns: 2025-10-31, 31/10/2025

Impact

• Who benefits: Users working with multilingual documents
• Priority: Medium
• Complexity: Low-Medium