Pure-Go {{path.dot.notation}} placeholder engine + unit tests
(t-paliad-215, design docs/design-submission-generator-2026-05-19.md
§6). Chosen over github.com/lukasjarosch/go-docx because that library
treats sibling placeholders inside one <w:t> run as nested and
refuses to replace them — patent submissions routinely carry multiple
placeholders per paragraph (party blocks especially), so the library
is a non-starter.
Two-pass strategy preserves run-level formatting on the common path:
1. Pass 1: regex replace inside each <w:t>…</w:t> independently —
no format loss for the 99% case where placeholders are intact.
2. Pass 2: paragraph-level merge for paragraphs that still contain
orphan "{{" or "}}" markers (Word fragmented the placeholder
across runs).
Missing placeholders render [KEIN WERT: <key>] / [NO VALUE: <key>]
markers so the lawyer sees the gap in Word rather than getting a 400.
Tests cover: single-run, multi-per-run (the go-docx failure mode),
cross-run merge, missing-marker (DE+EN), XML escaping of special
chars, non-document zip entries preserved, placeholder regex
grammar.
