fix(docx): give a paragraph opening a row's column the gap above its first line out of the space above the row

[DemchaAV]

Why

Word sets a paragraph's exact lines one height apart, so the page's gap between lines goes inside each line. A paragraph of n lines then holds one gap too many. applyLineGap takes that gap off the space above the paragraph, or off a table cell's top padding (takeFromTheTopOfItsCell).

A paragraph opening a column of a row of columns, or of a stack's columns, has neither. Its gaps were shared out over its lines instead, so its lines stood closer together than on the page:

• EditorialProposal's goal cells, three lines each, stood 1.46 and 0.45pt low and 0.56pt high in Word, and 1.35 and 0.35pt low and 0.65pt high in LibreOffice.
• OrangeOps' degree, two lines beside its badge, stood 0.45pt low and 0.45pt high in Word, and 0.30pt low and 0.55pt high in LibreOffice 24.2.

What changed

• The gap from above the row. takeFromAboveItsRow takes what neither the space above nor a padding holds from the space above the row. That space is the paragraph before the table: its space below, and its space above too when it is an empty separator.
• The lift. The paragraph notes the amount in raisedRows, as text standing above its cell does. raiseRows then lifts the row out of that space, and liftEachCell starts the row's other cells as much lower inside, so they keep their place. The paragraph's lines are written with the whole gap, the page's distance apart.
• Held rows. A row held to a height (trHeight) is held as much taller (holdTheLiftedRowTaller). Held as it was, a lifted row that its content does not fill ends higher by the lift. SerifHeadline's certifications, five columns of one row held at the page's height, otherwise stood the achievements under them 1.3pt high in Word.
• A floor. The lift only applies where it raises the first line half a point or more above where sharing the gaps out sets it. The line starts higher by the gap and grows by its share of it, and Word sets its baseline four fifths of the way down. A smaller rise left the lines higher than shared out where neither their position nor anything under them lowered them, and a cell's last paragraph has nothing under it. EditorialProposal's phase descriptions, 0.6pt short across two lines, stood 0.3pt high when lifted; their gaps stay shared out.
• Where it applies. Only the first row of a row of columns or of a stack's columns (rowsLiftedForTheirGaps, new). Not a row opening its page, and not in an overlay.
• Columns that open with a table. liftEachCell starts a cell that opens with a table lower inside below a hairline paragraph that holds the lift (startLowerAbove). A column painted as a panel is written as a table at the top of its cell, and a table has no space above it in Word, so before this such a column rose whole with its row. The existing lift for text standing above its cell goes through the same path.
• One reading of the space above. raiseRows' reading of the space above a table is extracted into spaceAbove, which both callers use.

Measured

• 5 of the corpus's 62 DOCX change: cv-orange_ops, cv-serif_headline, invoice-workspace, proposal-editorial and proposal-northline.

• Lines that moved by more than 0.05pt:

  Editor	Nearer the page	Further from it
  Word	40	5
  LibreOffice on Windows	44	0

• EditorialProposal's goal cells:

  Line	Word	LibreOffice on Windows
  first	1.46 → 0.14pt	1.35 → 0.25pt
  second	0.45 → 0.09pt
  third	−0.56 → 0.16pt	−0.65 → 0.25pt

  Its 90th percentile goes from 0.41 to 0.22pt in Word and from 0.65 to 0.35pt in LibreOffice.

• OrangeOps' degree, first line and second:

  • Word: 0.45 / −0.45 → −0.27 / −0.21pt.
  • LibreOffice 24.2: 0.30 / −0.55 → −0.20 / −0.20pt.

• NorthlineProposal's goal cells: Word 0.59 / −0.39 → 0.11 / 0.09pt.

• SerifHeadline's certification titles: Word 1.33 → 0.49pt.

• WorkspaceInvoice's note: Word 0.70 / −0.55 → −0.26 / −0.31pt.

• Of the five lines further in Word:

  • three move one step of Word's 0.12pt grid: two in OrangeOps' entry under its degree, and one of NorthlineProposal's;
  • two of NorthlineProposal's descriptions move past the page. They stand 0.16 and 0.22pt low, where they stood 0.08 and 0.14pt high.

• The report's 969 notes over the corpus are unchanged.

• This PR's CI run measures LibreOffice 24.2 on Linux:

  • the same five documents move;
  • 46 lines nearer the page, 2 further by 0.05pt;
  • two medians nearer;
  • acceptance stays at 53 of 62.

• The Word and Windows LibreOffice baselines are rewritten for the five documents. The Linux LibreOffice baseline follows from that run.

Verification

• DocxLineGapAboveTheRowTest adds 7 tests:
  • a row's column takes the gap from above the row, its neighbour starting lower;
  • a row with no space above it shares its gaps out;
  • a column opening with a panel starts lower, below a hairline;
  • a row opening its page is not lifted;
  • a gap too small for the line's position to take back is shared out;
  • a stack's column takes the gap too;
  • a held row is held as much taller as it is lifted.
• Undoing any one part fails the suite:
  • nothing taken above the row;
  • no floor;
  • a held row not grown;
  • a stack's columns not registered;
  • the space above not counted;
  • a column opening with a table left to rise;
  • any table's first row lifted.
• ./mvnw -B -ntp clean verify → BUILD SUCCESS.

Lane: shared-engine (render-docx semantic backend). No public API change.