python-docx find/replace fails on fragmented runs

Word docx files often fragment text across many small <w:t> elements inside multiple <w:r> runs because of tracked changes, autocorrect, and editor history. Find-and-replace on individual <w:t> elements silently fails when the search string spans element boundaries (eg. a date stored as <w:t>March 2</w:t><w:t>2</w:t><w:t>, 2026</w:t>). The robust fix is to rewrite the paragraph entirely: keep the <w:pPr> child, remove all <w:r> children, then add fresh runs with the new content and <w:br/> line breaks. Mixing single-element replacement with paragraph rewrites in the same file also corrupts insertion positions because newly added paragraphs land after the giant block paragraph, not where labels appear visually.