Add automatic Hebrew/Arabic RTL text and paragraph alignment

[daniel-efrat]

What and why

Add automatic Hebrew/Arabic RTL text support and paragraph alignment. New text detects each paragraph’s base direction from its first strong Unicode character, shapes Arabic and Hebrew in RTL runs, and lays out mixed text and numbers in visual order while preserving logical text storage.

New paragraphs automatically align right for RTL and left for LTR, including point, area, and path text. The Paragraph panel exposes Automatic alignment; explicit alignment choices remain available, and existing documents retain their saved alignment. Caret movement, hit testing, selections, editing, and undo follow the updated layout.

Bidirectional SVG text is outlined with a warning to preserve its appearance; native documents retain editable text. Rendering requires an installed font covering the script. Explicit direction overrides, dual caret affinity at mixed-direction boundaries, and RTL tab refinements remain follow-up work. No fonts or assets are added.

How it was tested

• cargo xtask ci passes all seven gates, including workspace tests and WASM.
• Regression coverage for RTL shaping, mixed scripts/numbers, combining marks, wrapping, caret navigation, automatic per-paragraph alignment, explicit overrides, serialization, editing/undo, SVG export, and the Paragraph panel.
• Inspected CLI-rendered Hebrew, Arabic, and mixed-text proofs and the native app’s automatic right-alignment state.
• Verified native save/reopen preserves the rendered proof.

Checklist

• cargo xtask ci passes (fmt, clippy, tests, assets, brands, layers, wasm).
• No panics in shipped code; errors follow the project’s fallible handling conventions.
• Clean-room: nothing copied from Adobe products or GPL/AGPL code.
• Every new asset has a row in ASSETS.md (no new assets).

[bflatastic]

Thank you so much @daniel-efrat, merged! Hebrew and Arabic now shape and lay out right to left, with mixed scripts and numbers in visual order and caret, selection and editing following them. It's a big step for VectorCraft. If you're not on our Discord yet, come say hi: https://discord.gg/artcraft

I rebased it on main (resolving it against the Japanese composition work that landed at the same time) and added two commits on top to match Illustrator's model and keep older builds working:

• Paragraph Direction instead of an "Automatic" alignment toggle: Illustrator has Left-to-Right / Right-to-Left Paragraph Direction (shown with the Middle Eastern / Indic options), and its alignment buttons stay physical.
  • Each text object has a Paragraph Direction. When it isn't set, the direction comes from each paragraph's first strong character, as in your PR.
  • The Paragraph panel gets the two direction buttons; the icons are new, original and listed in ASSETS.md.
  • text.setFormat takes direction: "auto" | "leftToRight" | "rightToLeft".
  • New type still aligns to the start of its direction. Imported text (PDF, SVG, DXF, EMF) keeps Left as before.
• Older builds: files saved with that alignment write a value v0.4.0 knows (Right or Left) plus an optional justify_auto flag. Without this, every new file containing text would fail to open in released builds.
• Speed:
  • Plain left-to-right text skips the bidi algorithm entirely.
  • Bidi now runs once per paragraph (it ran in shaping and up to 4× for path type).
  • Han and kana are no longer split into separate shaper calls.
• Fixes:
  • Hebrew and Arabic imported from PDF, including our own exports, came back mirrored. Import now restores logical order.
  • Vertical type is no longer marked right to left, so its caret no longer runs backwards.
  • Paragraph Styles with an alignment now replace an Auto one.
• Docs: ROADMAP, README and docs/development.md.

Checked live: Hebrew and Arabic are right-aligned at the anchor, with punctuation, digits and parentheses placed correctly and Arabic joined. Over MCP, text.setFormat {direction: "rightToLeft"} works, and bad values return clean errors. Still to come: Character Direction, digit types, kashidas, the Middle Eastern composers, and editable bidi text in SVG export (it's outlined with a warning for now).