Improve LaTeX template in static/en/mystery.template.tex

[coderabbitai]

Based on suggestions from this comment, the LaTeX template can be improved to enhance the table structure and robustness.

Suggestions include:

1. Using a robust width calculation using \dimexpr.
2. Better column spacing using @{} and @{\hspace{1em}}.
3. Proportional column widths with p{0.3\linewidth}.
4. Consistent horizontal lines.

Original PR: #13

Requester: @neuromancer

[coderabbitai]

Regarding the hardcoded column widths in the generate_latex_weapons_table function, making the column widths configurable would improve flexibility. This enhancement can be addressed in a future PR.