fix: add explicit encoding to open() calls for cross-platform portability

[KeloYuan]

Problem

Python's open() uses locale-dependent encoding by default, which varies across platforms:

• macOS/Linux: typically UTF-8
• Windows: typically cp1252 or other locale-specific encoding

This means code that works perfectly on macOS/Linux can silently corrupt data on Windows (and vice versa). Since Python 3.15, the default will change to UTF-8, but for now it's best practice to be explicit.

PEP 686 (Python 3.15+) will make UTF-8 the default, but explicit encoding is recommended for all current Python versions.

Changes

Added encoding="utf-8" to text-mode open() calls in 5 files:

File	Line	Purpose
searches/tabu_search.py	52, 91	Reading graph adjacency data
data_structures/arrays/sudoku_solver.py	209	Parsing Sudoku puzzles
strings/word_patterns.py	49	Loading dictionary file
data_compression/huffman.py	29, 81	Reading/writing compressed text
strings/detecting_english_programmatically.py	10	Loading English dictionary

Testing

All existing tests pass — no behavioral change for correct UTF-8 files.

[algorithms-keeper]

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