Deduplicate and clean up command tables for MathML parser

[fibonatto]

Problem

Within src/math.c, the LaTeX-to-MathML parser currently has duplicated entries in the command table (e.g., multiple "theta", "sigma", etc.), which leads to unnecessary scans, unnecessary binary size, and the potential for future maintenance errors or inconsistent mappings.

Proposed Solution

• Audit the MathML command table for duplicates and redundant entries
• Ensure each command appears exactly once with the correct MathML mapping
• Add (or update) a test verifying the table contains only unique entries
• Refactor table structure for maintainability if necessary

Acceptance Criteria

• All command tables are deduplicated
• Unique mapping for each supported LaTeX command
• Tests (or linter) would fail on future accidental duplicates