Add Watermark / Update Watermark can now move the mark from the page
centre by a horizontal and a vertical offset in points (right and up).
- edit: add_watermark refuses a non-finite offset instead of writing it
into the content stream; tests for the placement and the refusal.
- automation: doc_watermark takes offset_x and offset_y (clamped to
+-20,000 points); a test saves, reopens and measures the text moving.
- ui-egui: an "Offset from centre" row with Horizontal and Vertical
fields; the preview follows it for text and for picture watermarks.
- i18n: "Offset from centre" in the catalogs that have a coverage test
(ar, bg, de, fr, hu, it, ja, pt-br, ru, uk, zh-hans); hashes updated in
ATTRIBUTION.toml.
- parity and roadmap: edit.watermark-appearance stays partial (no offset
from the page edge, no print/screen-only variants, no repeat); image
and PDF watermarks no longer listed as missing; progress log line.
Co-authored-by: Brandon Thomas <echelon@gmail.com>
b752827162