Reject trailing characters in hashes and encoded values

[xiehuanyi]

Hash and encoding validators accept a final newline because the $ regular expression anchor can match immediately before it. For example, sha256("a" * 64 + "\n") currently returns True, although the input contains a character outside the digest.

Use re.fullmatch() for the six digest validators and four encoding validators. This preserves the accepted alphabets, case handling, and padding rules while requiring the entire value to match. The regression tests cover trailing newlines, CRLF, spaces, and extra lines across all ten validators.

Validation: the new tests produced 10 failures on unmodified master; after the fix, all 935 tests pass. Ruff lint, formatting checks for the changed files, and the complete Pyright check pass with Python 3.14.6. No other interpreter versions were run locally.

Developed, reviewed, and tested with AI assistance.

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