fix(docx): name in the report what a container written as its contents leaves of its layout

[DemchaAV]

Why

A container the DOCX export writes as its contents left part of its own layout out of the Word file and said nothing, while DocxExportReport promises to name every loss:

• a canvas's caption set at its middle came out at its top, with everything under it risen to meet it;
• a band bled to the page's edges stopped at its box;
• a column fixed narrower than its band ran its text the band's width;
• a line drawn in the flow and kept with the next block could end a page without it.

DocxNodeFieldLedgerTest listed each of these as a gap.

What changed

• inThePagedFlow() says where the page keeps a block with the next and bleeds a section's paint toward its edges: in the flow it lays out page by page, the body and the panels in it. Everything else is a box the page places:
  • an overlay (overlayDepth);
  • a row's or a table's composed cell, or a layer stack's column (slotDepth, raised in writeCellNodes and writeLayerColumns).
• canvasLosses names what a canvas written as its contents leaves out. Its drawings stand where it places them; what it writes is written one block after another inside its margin and padding.
  • Places: named unless it stacks what it writes from its corner, each block at the foot of the one before.
  • Height: named where the canvas stands in a flow (overlayDepth - oneLayerDepth == 1, a stack of one layer being no overlay), has a placement to measure by, and something follows it there other than a page break (followedInFlow).
    • followedInFlow is kept by writeChildren, by writeContainerBody for a box's last child, and by the loop over the roots.
    • A timeline's marker is a canvas alone in its row's cell, and gets no note.
  • Width: named where a block it writes holds a paragraph or a list and the canvas is narrower than the column.
• A painted section's bleed is named in the paged flow, on every page and every side.
• A layer stack's column names a fixed width narrower than its band (writeLayerColumns).
• A line drawn in the paged flow and kept with the next block names the keep, unless the next block is a page break. A drawing writes no paragraph to keep, and is anchored in a paragraph near it, so a page can end between it and the next block, whatever that block is.
• The ledger:
  • 6 node fields move from a gap to REPORTED: a canvas's width and placements, a section's bleed, a line's keep, and a section's and a container's fixed width.
  • A canvas's clipPolicy moves to INERT: the page clips no canvas, and CanvasLayerDefinition emits no clip. INERT's Javadoc now covers a field the page does not apply.
  • A canvas's height stays a gap: as its row's tallest cell, or ending a band or a layer stack's column, it is not yet named.
  • 15 node-field gaps remain, each named.
• The recipe (the sections and containers row, and a new "A canvas → its contents" fallback), the capability matrix (the layer stack row) and the CHANGELOG say what each note names.

Verification

• ./mvnw -B -ntp install -pl :graph-compose-render-docx → BUILD SUCCESS: 1030 tests, 0 failures, 1 skipped (the property-gated fidelity probe).
• DocxFlowContainerReportTest is new, 16 tests. A note on a container is checked whole; a phrase added to a drawn line's note is checked by how the note ends.
  • Canvas notes:
    • a canvas names its places, room and width;
    • one that only draws names its room;
    • one in a stack of one layer names its places and room.
  • Canvases that get no note:
    • one writing a spacer at its corner as tall as it;
    • one stacking what it writes from its corner;
    • one nothing follows;
    • one before a page break;
    • one composed in a table cell;
    • a timeline's markers.
  • Bleed:
    • a bled panel names its bleed, and the body XML equals the unbled one's;
    • one running onto a second page names it too;
    • a bled panel in a layer, and an unpainted bled section, get no note.
  • Keep:
    • a kept line names the keep before a table, before a paragraph and in a panel;
    • in a row's cell, or before a page break, it does not.
  • A column fixed narrower than its band names its width.
• The tests fail without the code they cover. Removed in turn or together, each of these made its tests fail:
  • the one-layer adjustment;
  • the followed check;
  • the page-break exceptions;
  • the slot depth;
  • the placement check;
  • the stacking check.
• The DOCX bytes do not change. The 62 corpus documents exported deterministically are byte-identical to the export before the change: DocxFidelityCorpusTest -Dgraphcompose.docxFidelity=export, SHA-256 per file, 0 of 62 differ.
• Documentation and qa DOCX tests:
  • -pl :graph-compose-core -Dtest='com.demcha.documentation.**' → 166 tests, 0 failures;
  • qa documentation guards plus DocxPageZoneTest, DocxTransparentWrapperTest, TimelineRailAcrossBackendsTest and RtlAcrossBackendsTest → 52 tests, 0 failures.
• The full reactor gate was not run; no public API, POM or workflow file changed.

Lane: render-docx backend (report only, no change to what is written) plus tests and docs.