feat(pdf): revamp latex template

[ekassos]

Changed

• Change the default paragraph font size from 9.0pt to 9.5625pt to match Swift-DocC-Render's default body font size.
• Rework generated PDF chapter heroes, body text, headings, and table-of-contents section headings to use Swift-DocC-Render-derived typography, line heights, and spacing.
• Rework generated PDF block spacing so paragraphs, headings, lists, asides, code listings, images, and tables use DocC-style top-margin ownership instead of implicit LaTeX spacing.
• Render generated PDF code listings with DocC-style listing boxes, padding, borders, and code typography.
• Redesign generated PDF aside notes with DocC-style padding, label spacing, text color, left-border rendering, and breakable-page behavior.
• Refine generated PDF aside note borders so the left accent follows the rounded box corners instead of drawing as a square-edged rule.
• Rework generated PDF unordered, ordered, and term lists to use DocC-style list spacing, indentation, and nested paragraph rendering.
• Rework generated PDF tables to use DocC-style cell padding, borders, body typography, and measured column widths instead of the previous stretched table layout.
• Rework generated PDF table-of-contents chapter links to use DocC-style topic link blocks with aligned icons, subtitle indentation, and print page-reference leaders.
• Align generated PDF inline image spacing with DocC content-node spacing and surrounding block-state handling.
• Improve handling of special characters in generated PDF code blocks and inline text with PUA escapes.

Fixed

• Fix an issue where generated PDF code listings could be missing a double pipe (||) because of an unintended formatting escape.

Closes #153, closes #154, closes #155, closes #156, closes #157