fix(docx): write a row's fill, outline and side borders, as a panel holding its columns

CHANGELOG.md

@@ -8,6 +8,45 @@ follow semantic versioning; release dates are ISO 8601.
 
 ### Public API
 
+- **A DOCX export writes a row's fill, outline and side borders, as a panel holding its
+  columns.** A row paints its box as a container does — `RowBuilder.fillColor`, `stroke`,
+  `borders` — and the export wrote its columns as a table with no shading or borders, naming the
+  paint as lost (`row paint`).
+  - **A row that paints is written as a panel**, as a painted container is: a table of one cell
+    carrying the fill as its shading and the outline and side borders as its borders, its
+    margins the row's padding, as a panel's are. The columns are a table nested in the cell,
+    laid out as the row's own less the padding the cell's margins hold; the panel holds the
+    row's height. The panel is kept whole across a page break, as the row is, and a row the
+    layout moves to a new page keeps the space above it there.
+  - **A corner radius squares**, and is named (`corner radius`), as a panel's is. A translucent
+    fill or border is flattened against what the page paints under it, and named.
+  - **What stands on the row is set on its fill.** A chip, a rule or a translucent panel in one
+    of its columns is flattened against the panel's shading as written, where it was flattened
+    against the page under the row.
+  - **Borders above and below are named.** Word draws them outside the panel's row, where the
+    page strokes them on the box's edge: where no space round the row takes them, what follows
+    stands up to their width lower (`RowNode`, `APPROXIMATED`). Measured, five rows with a 1pt
+    bottom border one under the other set what follows 5.4pt low in Word and LibreOffice: their
+    borders' 5pt, and a tenth of a point for each hairline paragraph Word needs between two
+    tables, as five containers with that border do. A top border wider than the row's padding
+    stands its columns that much lower too, where the space above does not take it, and the
+    note says so.
+  - **Still named as `row paint`**, its columns written alone:
+    - composed in a table cell, whose table draws its box as a shape where it frames no text;
+    - in a page zone's line;
+    - in a band of overlapping layers, or where a stack's column measures the space above or
+      below it to the text inside it, which the panel's margins would hold again;
+    - with a padding below zero, or a first or last column whose margin hangs into it;
+    - with a margin below zero above or below it, which its columns' table nets against its
+      padding and a panel does not, or at a side in a cell, where Word starts a table no further
+      left than the cell's text. In the body a row bleeding past the margin is its panel.
+
+  Measured in Word 16 and LibreOffice on a page of painted rows, a filled row's shading covers
+  the box the page fills, to a tenth of a point, and its text stands where the page sets it. No
+  row in the DOCX fidelity corpus paints its box, and the 62 documents are byte-identical. In
+  `DocxNodeFieldLedgerTest` a row's `fillColor`, `stroke` and `borders` stay `REPORTED`, for
+  the cases above.
+
 - **A DOCX export writes an auto-sized paragraph's text at the size the page fits it to.** The
   page fits a paragraph with `autoSize(...)` to the largest size its line holds, smaller or
   larger than its style's. The export wrote the text at its style's size: Word broke a shrunk
@@ -245,7 +284,9 @@ follow semantic versioning; release dates are ISO 8601.
   - **Where Word holds an opaque colour only** — a cell's shading, a border, a rule — the colour
     is flattened against what Word paints under it. Inside a panel or cell the export shaded, that
     is the shading as written; on the page, it is read from the layout: the fills drawn before the
-    block at its centre, a page background included, a row's own fill (which is not written) left
+    block at its centre, a page background included, a row's own fill (which is not written; since
+    written in the flow, as a panel: see "A DOCX export writes a row's fill, outline and side
+    borders, as a panel holding its columns") left
     out. Each is named in the report as `translucency`:
     - a panel's fill and borders, once per panel;
     - a table cell's fill and rules, once per table;
@@ -525,7 +566,8 @@ follow semantic versioning; release dates are ISO 8601.
     row is written as a table with no shading or borders, and a page zone's row as one line.
     Now `DROPPED`, `row paint`, naming which of them, and `rounded` where a corner radius
     rounds them; a row of no columns is named where the layout gives it height, as the page
-    paints only then. A row composed in a table cell is `DROPPED` where the cell drew none of
+    paints only then (since written in the flow, as a panel: see "A DOCX export writes a row's
+    fill, outline and side borders, as a panel holding its columns"). A row composed in a table cell is `DROPPED` where the cell drew none of
     its paint — round text it never draws any — and `APPROXIMATED` where the table drew
     shapes, since a cell's paint is drawn where it frames no text and the layout does not say
     which box is the row's;