Type: Paragraph Direction instead of an Automatic alignment toggle; bidi only where needed (review of #300)

Illustrator sets a paragraph's direction (Left-to-Right / Right-to-Left
Paragraph Direction in the Paragraph panel, with the Middle Eastern
options) and keeps its alignment buttons physical; it has no automatic
alignment toggle. So:

- ParaStyle.direction (None: from each paragraph's first strong
  character, as before; written only when set), the Paragraph panel's two
  direction buttons with Show Indic Options (original icons), and
  text.setFormat {direction: "auto"|"leftToRight"|"rightToLeft"}. The
  layout uses it as the base direction.
- The Automatic alignment check box is gone. Justify::Auto stays as the
  start of the paragraph's direction, set on new type only (text.create,
  the Type tools, with the mojikumi default in one new_type_para()):
  TextObject::point is Left again, so importers (PDF, SVG, DXF, EMF) keep
  their own alignment. The alignment buttons show what Auto resolves to.
- Bidi only where there is something right to left: plain paragraphs skip
  the algorithm (no per-layout allocation), it runs once per paragraph
  (shaping takes the paragraph's levels instead of recomputing them; path
  type computed it four times), and the shaper keeps Han, Hiragana,
  Katakana and Bopomofo in one segment (splitting at every change of
  script cost Japanese text a shaper call per kana-kanji switch).
- Vertical type keeps its logical order, so its glyphs and lines are not
  marked right to left (the caret no longer runs backwards down a column).
- PDF import puts Hebrew and Arabic, which PDFs (and VectorCraft's own
  export) draw in visual order, back in logical order with the direction
  that shows it as drawn; with bidi layout it came back mirrored.
- SVG import pins the direction SVG implies (left to right unless
  direction: rtl); SVG export also outlines right-to-left paragraphs.
- Docs (development.md), ROADMAP (folded into the Type entry, Type core
  row) and README updated; catalog rows for the new labels.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/development.md

@@ -180,26 +180,24 @@ CI runs a few dozen cases each. Before touching an importer, run a deeper search
 `PROPTEST_CASES=20000 cargo test --release -p vectorcraft-engine --test import_fuzz`. When it finds a
 panic, fix the code and add the input as a regular test.
 
-## Bidirectional type (M7.RTL)
+## Bidirectional type
 
-Horizontal point, area and path text automatically resolve paragraph direction using Unicode
-first-strong detection. Hebrew and Arabic runs shape right to left; embedded Latin and numbers
-retain their direction. Wrapping happens in logical order, followed by visual ordering of whole
-shaping clusters. Text commands, pasted text and the Type tool use the same layout; stored text,
-undo and style byte ranges remain in logical order. New text defaults to automatic alignment:
-Hebrew/Arabic paragraphs align right and grow left from a point anchor, while LTR paragraphs
-align left. Alignment is resolved again during edits and independently for each paragraph.
-The Paragraph panel highlights the resolved alignment and provides an Automatic alignment toggle.
-Explicit Left/Center/Right choices override detection; `text.setStyle {justify: "auto"}` restores
-automatic mode. Saved documents retain the mode; existing explicit alignments are preserved.
+Point, area and path type lay out Hebrew and Arabic with the Unicode bidirectional algorithm
+(`unicode-bidi`, in `crates/text/src/layout.rs`). Each paragraph's base direction is its
+`ParaStyle::direction` (Paragraph panel › Left-to-Right / Right-to-Left Paragraph Direction, shown
+with Preferences › Type › Show Indic Options; `text.setFormat {direction}`), else its first strong
+character. Text is shaped in logical order, right-to-left runs right to left (`shape.rs` splits
+segments by bidi level and script), lines are broken in logical order and then each line's whole
+shaping clusters are put in visual order. Stored text, undo and style ranges stay logical; the
+caret, selection, hit testing and arrow keys follow the visual order. A paragraph with nothing
+right to left in it skips the algorithm, so plain text pays nothing for it.
 
-Combining marks stay with their bases and Arabic uses the font's contextual forms and ligatures.
-Use an installed font covering the script; no new fonts are bundled. Web builds need a font with
-Hebrew/Arabic coverage supplied through the existing font setup. SVG export outlines bidirectional
-text to preserve its appearance; native files retain editable text. PDF and raster exports use the
-same positioned glyphs as the canvas.
+Alignment buttons are physical (Align Left is left in either direction). New type
+(`text.create`, the Type tools) is aligned `Justify::Auto`, the start of each paragraph's direction:
+Hebrew grows to the left of a point type's anchor. Imported text keeps its own alignment, and SVG
+import pins the direction SVG implies (left to right unless `direction: rtl`).
 
-Remaining refinements: explicit paragraph direction overrides, dual caret affinity at mixed-direction
-boundaries, RTL tab-stop conventions, and editable bidirectional SVG export. Vertical type retains
-its existing logical column order. Unicode direction detection is script based, not a language or
-keyboard-layout classifier.
+Vertical type keeps its logical order down the column. SVG export outlines text with right-to-left
+lines (with a warning) until it is written with `direction`/`unicode-bidi`; PDF and raster exports
+use the laid-out glyphs. No font is bundled for these scripts: the installed fonts' fallback
+covers them (the web build needs a font with that coverage).