Adapt parser and tests to new sompyler AST slot names

Sompyler commit c3b51bc renamed slots across the board:
- offset.stem_note → line.stem_note (parentSlot 'offset' → 'line')
- motif.stem_note → line.stem_note (parentSlot 'motif' → 'line')
- clause.note/pause/stack → seq.note/pause/stack (parentSlot 'clause' → 'seq')
- stem_note.chain is now a real hierarchical node (depth 04) between
  line.stem_note and chain.clause; clauses are now its children, not
  direct children of stem_note

Also adds:
- offset.motifs[] for line.motif invocations at tick positions
- stem_note.writeToName from stem_note.write_to positional
- adjacent prop already stored; new tests verify True/False/absent

PaneFO.js: show offset motif invocations inline (label + chord)
test-parser.mjs: update synthetic fixtures to new depths/slot names;
  add tests for line.motif, stem_note.write_to, adjacent prop

static/ast-parser.js

@@ -439,17 +439,22 @@ function buildOffset(node) {
         type: 'offset',
         tick: node.props.tick,
         stemNotes: [],
+        motifs: [],
         unknownProps: collectUnknownProps(node.props, new Set(['tick'])),
     };
     for (const child of node.children) {
-        if (child.parentSlot === 'offset' && child.slot === 'stem_note')
+        if (child.parentSlot === 'line' && child.slot === 'stem_note')
             offset.stemNotes.push(buildStemNote(child));
+        else if (child.parentSlot === 'line' && child.slot === 'motif')
+            offset.motifs.push({ label: child.positionals[0], chord: child.props.chord ?? null });
     }
     return offset;
 }
 
 function buildStemNote(node) {
     const KNOWN = new Set(['pitch', 'eff_length', 'adj_stress', 'adjacent']);
+    const chainNode = node.children.find(c => c.parentSlot === 'stem_note' && c.slot === 'chain');
+    const writeToNode = node.children.find(c => c.parentSlot === 'stem_note' && c.slot === 'write_to');
     return {
         type: 'stem_note',
         pitch: node.props.pitch,
@@ -458,8 +463,9 @@ function buildStemNote(node) {
         adjStress: node.props.adj_stress ?? null,
         length: null,
         weight: null,
-        chainText: node.children.find(c => c.slot === 'chain')?.props._tmp_string ?? '',
-        clauses: node.children
+        chainText: chainNode?.props._tmp_string ?? '',
+        writeToName: writeToNode?.positionals[0] ?? null,
+        clauses: (chainNode?.children ?? [])
             .filter(c => c.parentSlot === 'chain' && c.slot === 'clause')
             .map(buildClause),
         isDirty: false,
@@ -472,9 +478,9 @@ function buildClause(node) {
         type: 'clause',
         index: node.positionals[0] ?? 0,
         repeat: node.props.repeat ?? null,
-        notes:  node.children.filter(c => c.slot === 'note'  && c.parentSlot === 'clause').map(c => ({ ...c.props })),
-        pauses: node.children.filter(c => c.slot === 'pause').map(c => ({ length: c.props.length })),
-        stacks: node.children.filter(c => c.slot === 'stack').map(c => ({
+        notes:  node.children.filter(c => c.slot === 'note'  && c.parentSlot === 'seq').map(c => ({ ...c.props })),
+        pauses: node.children.filter(c => c.slot === 'pause' && c.parentSlot === 'seq').map(c => ({ length: c.props.length })),
+        stacks: node.children.filter(c => c.slot === 'stack' && c.parentSlot === 'seq').map(c => ({
             length: c.props.length, netlength: c.props.netlength,
             notes: c.children.filter(cn => cn.slot === 'note').map(cn => ({ ...cn.props })),
         })),
@@ -489,7 +495,7 @@ function buildMotif(node) {
         unknownProps: collectUnknownProps(node.props, new Set(['label'])),
     };
     for (const child of node.children) {
-        if (child.parentSlot === 'motif' && child.slot === 'stem_note')
+        if (child.parentSlot === 'line' && child.slot === 'stem_note')
             m.stemNotes.push(buildStemNote(child));
     }
     m.isStatic = m.stemNotes.length > 0 && !m.stemNotes.some(sn => Number.isInteger(sn.pitch));

static/components/PaneFO.js

@@ -193,8 +193,11 @@ export const PaneFO = {
                         fields: [
                             { key: 'tick', value: node.tick, editable: false },
                             { key: 'stem notes', value: node.stemNotes.map(snLabel).join(', ') || '—', editable: false },
+                            node.motifs?.length
+                                ? { key: 'motifs', value: node.motifs.map(m => m.chord ? `${m.label}(${m.chord})` : m.label).join(', '), editable: false }
+                                : null,
                             ...unknownPropFields(node),
-                        ],
+                        ].filter(Boolean),
                         onChange: null,
                     }),
                 );