Add Bazeries cipher codec

[Copilot]

Checklist

• No unrelated changes
• Codec is new (not already implemented)
• Tests included (if cannot be automated with tests/test_generated)
• Documentation (included in the right page in docs/pages/enc)

Description

The Bazeries cipher (Étienne Bazeries, ~1901) combines two 5×5 Polybius squares with a digit-based transposition. A numeric key is spelled out in English to build the second square's alphabet; the key's digits define group sizes for reversing plaintext segments before cross-square substitution.

src/codext/crypto/bazeries.py

• Numeric key (e.g. bazeries-137): spells out "ONE HUNDRED THIRTY SEVEN" → cipher alphabet; digits [1,3,7] → transposition group sizes
• Keyword key (e.g. bazeries-CIPHER): keyword builds the cipher alphabet; word lengths → group sizes
• Default key is 137 when none is provided
• J→I merged per standard 5×5 square convention; non-alpha characters stripped

src/codext/crypto/__init__.py

• Added from .bazeries import *

>>> import codext, codecs
>>> codecs.encode("HELLO", "bazeries-137")
'TSSUB'
>>> codecs.decode("TSSUB", "bazeries-137")
'HELLO'
>>> codecs.encode("THEQUICKBROWNFOX", "bazeries-137")  # round-trips cleanly
'LFUTBGNYEIMQBDAW'

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add new encoding: bazeries</issue_title>
<issue_description>### Description

The Bazeries cipher is an encryption system created by Étienne Bazeries that combines two Polybius grids (square arrays of letters) and a transposition supercipher based on a number or keyword.

Reference

https://www.dcode.fr/bazeries-cipher</issue_description>

<agent_instructions>Please propose an implementation that satisfies the guideline in docs/pages/howto.md.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Add new encoding: bazeries #33

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