M7: Every-line Composer for ragged text

Illustrator's Every-line Composer balances the breaks of the whole
paragraph for left/centre/right aligned text too, not only justified
text. VectorCraft only composed justified area text; ragged text was
always broken greedily.

- Model: ParaStyle.composer (vectorcraft_doc::Composer, re-exported by
  vectorcraft-text), Every-line by default like Illustrator, saved only
  when Single-line. layout() reads it from the object;
  LayoutOptions.composer is now an Option override for tests.
- Composer: the justified gate is gone. Ragged lines never shrink (a
  line that doesn't fit ends the node), badness is 100*r^3 with r = the
  line's leftover space over a rag zone of 1/6 of the width (finite for
  lines without spaces); the last line is free unless shorter than 1/3
  of the width (measured in zones of 1/3), so a lone short word on the
  last line pulls a word down. Hyphens cost 25 in ragged text (50 in
  justified). Knuth-Plass fitness classes with adjacency demerits
  (justified 10000, ragged 1000). Lines past the last width change
  share one node key, active nodes are capped (4096) and paragraphs
  over 200k glyphs break single-line, so work stays bounded; ragged
  tries a tolerance of one rag zone, then any fitting breaks, then
  falls back to greedy.
- text.setFormat {composer: "singleLine"|"everyLine"}; the Paragraph
  panel menu's composer items work with a check mark (Reset Panel goes
  back to Every-line).
- Tests: ragged Every-line moves "or" down in "Destroy all creatures
  with toughness X or less." where greedy leaves "less." alone; the rag
  of long paragraphs is no worse than greedy (sum of squared leftover
  and of neighbour differences); Single-line is greedy; the 10k-char
  layout budget covers ragged text; command test with undo; native
  format round trip (rich_session's text is now Single-line).
  No existing test needed changing: the justified tests and
  hyphenated_layout_adds_hyphens (ragged, now Every-line) still pass.

Auto alignment (start of the paragraph direction) is ragged; a wrapped
line's Mojikumi flush opening bracket gives its half em back to the
composer, as in the line loop; tests cover Auto in both directions.

Layout of 10k chars, release: justified Every-line 5.6 ms, ragged
Every-line 5.8 ms, ragged Single-line 4.8 ms.

crates/engine/src/cmd/panelcmds.rs

@@ -2,7 +2,7 @@
 //! Character/Paragraph attributes.
 
 use serde_json::{Value, json};
-use vectorcraft_doc::NodeKind;
+use vectorcraft_doc::{Composer, NodeKind};
 use vectorcraft_geom::{Rect, Vec2};
 
 use super::*;
@@ -43,7 +43,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Character / Paragraph",
             [],
             None,
-            "{ids?|id?, kerning?: 1/1000 em|\"auto\", baselineShift?: pt, hScale?: %, vScale?: %, rotation?: deg, underline?, strikethrough?, allCaps?, smallCaps?: bool, position?: \"normal\"|\"superscript\"|\"subscript\" (sizes from Document Setup), leftIndent?, rightIndent?, firstLineIndent?, spaceBefore?, spaceAfter?: pt, hyphenate?: bool, mojikumi?: \"none\"|\"lineEndHalf\" (Japanese punctuation spacing), direction?: \"auto\"|\"leftToRight\"|\"rightToLeft\" (paragraph direction; auto: from each paragraph's first strong character), leadingModel?: \"romanBaseline\"|\"emBoxTop\" (leading measured baseline to baseline, or em box top to top), charAlign?: \"romanBaseline\"|\"emBoxTop\"|\"emBoxCenter\"|\"emBoxBottom\" (where characters smaller than the largest on their line line up with it), burasagari?: \"none\"|\"standard\"|\"forced\" (Paragraph panel menu › Burasagari None/Regular/Force: an East Asian comma or full stop ending an area type line hangs outside it: when it doesn't fit, or always; new type: \"standard\")}",
+            "{ids?|id?, kerning?: 1/1000 em|\"auto\", baselineShift?: pt, hScale?: %, vScale?: %, rotation?: deg, underline?, strikethrough?, allCaps?, smallCaps?: bool, position?: \"normal\"|\"superscript\"|\"subscript\" (sizes from Document Setup), leftIndent?, rightIndent?, firstLineIndent?, spaceBefore?, spaceAfter?: pt, hyphenate?: bool, mojikumi?: \"none\"|\"lineEndHalf\" (Japanese punctuation spacing), direction?: \"auto\"|\"leftToRight\"|\"rightToLeft\" (paragraph direction; auto: from each paragraph's first strong character), leadingModel?: \"romanBaseline\"|\"emBoxTop\" (leading measured baseline to baseline, or em box top to top), charAlign?: \"romanBaseline\"|\"emBoxTop\"|\"emBoxCenter\"|\"emBoxBottom\" (where characters smaller than the largest on their line line up with it), burasagari?: \"none\"|\"standard\"|\"forced\" (Paragraph panel menu › Burasagari None/Regular/Force: an East Asian comma or full stop ending an area type line hangs outside it: when it doesn't fit, or always; new type: \"standard\"), composer?: \"singleLine\"|\"everyLine\" (line breaking, Every-line by default)}",
             has_doc,
             set_format
         ),
@@ -219,10 +219,19 @@ fn set_format(s: &mut Session, p: &Value) -> Result<Value> {
         "leadingModel",
         "charAlign",
         "burasagari",
+        "composer",
     ];
     if !keys.iter().any(|k| p.get(*k).is_some()) {
         return Err(bad(C, "nothing to change"));
     }
+    let composer = match p.get("composer") {
+        None | Some(Value::Null) => None,
+        Some(v) => Some(match v.as_str() {
+            Some("singleLine") => Composer::SingleLine,
+            Some("everyLine") => Composer::EveryLine,
+            _ => return Err(bad(C, "composer must be \"singleLine\" or \"everyLine\"")),
+        }),
+    };
     let (position, small_caps) = super::docsetup::script_params(p, &s.doc()?.doc.setup, C)?;
     let char_align = super::textedit::char_align_param(p, C)?;
     let mojikumi = match p.get("mojikumi") {
@@ -329,6 +338,9 @@ fn set_format(s: &mut Session, p: &Value) -> Result<Value> {
             if let Some(v) = burasagari {
                 para.burasagari = v;
             }
+            if let Some(v) = composer {
+                para.composer = v;
+            }
             super::typecmd::refresh_bounds(t);
         }
         Ok(())