fix(mtext): tab stops are column-relative and align-aware when wrapping

Two defects in tabbed fields inside a multi-column MText:

- Stop positions are relative to the paragraph's own left edge, but the
  tab logic compared them against the column-absolute `cursor_x`. In a
  second column `cursor_x` already carries the column offset, so no stop
  ever matched and the field shot off to the default 4-em grid, way past
  the page. Measure against the column's `box_left` instead.
- A field after a center/right/decimal tab aligns on the stop, reaching
  only part of its width to the right, but word-wrap flushed it left and
  wrapped it off the line by its full width — dropping a wide decimal
  number onto a fresh, un-tabbed line. Don't wrap the field that follows
  an aligning tab.

Picks up acadrust b16137f (decimal stop position parse).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Cargo.lock

@@ -73,7 +73,7 @@ checksum = "366ffbaa4442f4684d91e2cd7c5ea7c4ed8add41959a31447066e279e432b618"
 [[package]]
 name = "acadrust"
 version = "0.4.0"
-source = "git+https://github.com/OpenAEC-Foundation/acadifc?branch=main#162f1940ef9f7faaa9b6597e4b190be913b70d37"
+source = "git+https://github.com/OpenAEC-Foundation/acadifc?branch=main#b16137ff0143bf480edfbc8e12f89068a76316de"
 dependencies = [
  "ahash 0.8.12",
  "anyhow",