fix(docx): name timeline rails once and correct the ledger's fates - #950

Why

The DOCX export's report and its field ledger are the contract for what an export loses. Read against the code, a few of their statements were not true.

• A note twice. The timeline rail note was added once per layout pass fragment. Every rail shares the path @timeline-rail, so each timeline, and each page a rail runs onto, added the same note again. cv-terracotta_rail, with two timelines, carried it twice.
• WRITTEN, or a narrower case, for fields a path loses. DocxNodeFieldLedgerTest said these were written, though the report names their loss:
  • the geometry and paint of a drawing the export drops, which a note names. Among its reasons: no layout, a page zone, a gradient alone or nothing painted, a page no paragraph is written on;
  • with no layout, a paragraph's line spacing and a section's or a line's keeps;
  • a paragraph's line spacing in a page zone, where the zone's note says where its part stands;
  • keeps inside a panel the layout runs on to the next page (reportAKeepThePanelBreaks), and keeps composed in a table cell, where the table row is what is kept;
  • a page field's kind, style, padding and margin anywhere but on a page zone's line, where it is dropped.
• A page field's alignment. The ledger called it INERT, and TextAlign's centre and right "not applied" to a page field. PageFieldDefinition sets the field in a box a point wider than its number, so its alignment moves the number by up to that point. The capability matrix and the DOCX recipe said the same.
• Two losses no note names, stated as written:
  • A stand-in spacer. DocxLayerColumns takes a spacer level with another layer's content, in a band or a stack written as columns, as a stand-in. Where that content is not written in its place, the spacer is not written.
  • A paragraph composed in a table cell whose text no laid-out line carries. It gets no line gap (DocxLayoutMetrics.lineGap).
• A stale CHANGELOG bullet. A v2.5.0 entry still said a band opening with a list or a row loses the space above it. A later entry in the same section fixed that.

What changed

• DocxSemanticBackend: the rail note is added once per path per section.
  • Every fragment is still queued before the name is checked.
  • DocxDrawingAnchors.Owner("timeline rail", path) already reckons what no paragraph carries for all rails of that path together. One note now matches that one reckoning.
• DocxNodeFieldLedgerTest: the fates above name the path where the field is lost.
  • DRAWING_DROPPED for drawings, also inside RULE_WIDTH and RULE_TRANSLUCENCY;
  • KEEP for section and line keeps;
  • FIELD_OUTSIDE_A_ZONE for page fields;
  • two new gaps among the known cases: STAND_IN_LEFT_EMPTY on SpacerNode.height and LINE_GAP_UNREAD on ParagraphNode.lineSpacing.
• DocxValueFieldLedgerTest: TextAlign.CENTER/RIGHT drop "a page field's the page does not apply" and name a page field off a zone's line.
• Docs:
  • the capability matrix's page-zone row and the recipe's page-field sentence are corrected;
  • the stale CHANGELOG bullet now points to the entry that holds the space;
  • new CHANGELOG entries under Public API (the rail note) and Tests (the ledger).
• Not in this change: writing the stand-in spacer and the composed paragraph's line gap. This change only states them.

Verification

• DocxFlowContainerReportTest.twoTimelinesRailsAreNamedOnce (new). Two timelines with connectors give exactly one timeline rail note, and twice the anchored drawings of one timeline: both rails and their markers are drawn.
• Fail-closed: 5 sabotages, each run alone, all caught.
  • The rail named for every fragment again: the new test fails.
  • The stand-in gap removed from the known cases: the node ledger fails.
  • The unread line gap removed from the known cases: the node ledger fails.
  • A paragraph's line spacing left without an entry: the node ledger fails.
  • A TextAlign constant left without an entry: the value ledger fails.
• Corpus:
  • The 62 DOCX files are byte for byte the same.
  • The notes go from 1385 to 1384. The only note gone is cv-terracotta_rail's second timeline rail note.
• Gate:
  • ./mvnw -B -ntp clean verify -pl <core, render-pdf, render-docx, render-pptx, templates, testing, qa, coverage> -am → BUILD SUCCESS. Core 821, render-pdf 339, render-docx 2088, testing 5, render-pptx 142, templates 127, qa 1828.
  • The JDK 17 knowledge checks pass, and core javadoc has 0 warnings.
  • ./mvnw -f examples/pom.xml test → BUILD SUCCESS, 93 tests.
• After the last ledger, test and wording fixes (the test ledger and the docs only; the backend is unchanged since the gate):
  • ./mvnw verify -pl :graph-compose-render-docx → BUILD SUCCESS, 2088 tests;
  • the qa documentation guards → 28 tests, BUILD SUCCESS;
  • the claims, routes and stability checks pass.

Lane: shared-engine (render-docx): the report and the test ledger only. No public API change, and no change to the written DOCX.