feat(odf): draw a shape where its draw:transform puts it

[andiwand]

🤖 Generated with Claude Code

Stage 1 of #771, stacked on #795.

draw:transform (19.228) was not read at all, so a rotated, skewed or
matrix-placed shape was drawn unrotated — and a shape placed by a transform
rather than by svg:x/svg:y, which is what libreoffice writes for a rotated
one, was drawn at the origin. 25 occurrences over 4 files in the test corpus,
on draw:custom-shape, draw:frame and draw:path.

odf_geometry.cpp composes the operation list into one DrawingTransform —
four unitless numbers and a translation carrying a length, which is what
matrix(a b c d e f) means — and Frame, Rect, Line, Circle and
CustomShape hand it out. The renderer writes it as css, with
transform-origin:0 0, because css otherwise turns a box about its centre.
Composing rather than passing the string through is not optional: ODF angles
are radians where css wants degrees, and no input markup authors our output.

Two things the spec text does not settle

Both decided against libreoffice's own svg export of style-drawing-1.odp:

• The list applies to the shape left to right, so the translate in
  rotate (a) translate (x y) is not itself rotated. The other reading puts
  the shape's left edge at 22779; libreoffice reports 23084, which is what this
  one gives, to the unit.
• rotate is counter-clockwise for a positive angle, the opposite of svg's
  handedness in the same y-down space. Libreoffice writes rotate(-19.4) in
  degrees for the file's rotate (0.340164671213695).

Notes

• A transform is an element accessor rather than a GraphicStyle field because
  get_intermediate_style overrides down the element parent chain, which would
  leak a group's transform onto every child that carries none of its own.
• The four engines that implement FrameAdapter without a transform to give
  return nothing; ooxml's presentation adapter gets the TODO for a:xfrm.
• New public DrawingTransform and transform(), mirrored in the JNI, Apple
  and Python bindings.

Verification

odf_geometry_test.cpp, from string literals: composition order, radians and
handedness, the unit a translation keeps, and what is refused.

The reference-output pin is advanced: 6 files over 4 documents
(style-drawing-1.odp, presentation-yunation.odp,
Sealver Measurements.odg), each changed line differing by the inserted
transform / transform-origin declaration and nothing else.