fix: preserve pptx no-wrap auto-fit title spacing

[developer0hye]

What changed

• allow fixed PPTX text boxes with both no-wrap and auto-fit enabled to use the single-line scale-to-fit path
• add regression coverage for tight no-wrap auto-fit title boxes so the scaled Typst output matches the intended fixed-height PPT box

Why

• a classified PPTX fixture regressed on slide 2 where a no-wrap auto-fit title rendered too tall and overlapped the first list item

Validation

• cargo test --offline -p office2pdf fixed_page_textbox_tests
• rebuilt the CLI and regenerated the classified fixture PDF for visual verification of slide 2

Related: #111