Parser: support sompyler 10cad1f preamble (stage.*, articles.<subtype>, tuning.frequency_factors)

- Top-level dispatch switches on fqSlot (parentSlot.slot) so dotted top-level
  slots (`stage.cone`, `stage.voice`, `articles.<subtype>`) are matched.
- `stage_voice` -> `stage.cone` (new, one per score) + `stage.voice` (list).
- `article` -> `articles.<subtype>` (subtype stored on the article entry;
  first observed subtype is `defaults`).
- New `tuning.frequency_factors` child captured as `{ label, factors }`.
- buildModel un-nests preamble siblings that sompyler emits at depth 01
  under `00 tuning` via `with deeper_level("articles")` / `deeper_level("stage")`.
  Only `tuning`'s children are flattened; `instrument`'s implicit containers
  (`character`, `VOLUMES`, `TIMBRE`, `FM`, `AM`) are left untouched.
- Fixture test extended with 18 preamble assertions (172 total now pass).

static/ast-parser.js

@@ -118,24 +118,47 @@ export function buildModel(rawTree) {
         info: null,
         tuning: null,
         articles: [],
+        stageCone: null,
         stageVoices: [],
         instruments: [],
         bars: [],
     };
 
+    // Upstream uses `with deeper_level("articles"):` / `deeper_level("stage"):`
+    // implicit containers that emit no depth-00 header. Their depth-01 lines get
+    // nested under the preceding `00 tuning` by the depth-stack parser even
+    // though they are conceptually siblings of tuning. Un-nest them here.
+    const topLevel = [];
     for (const node of rawTree.children) {
-        switch (node.slot) {
+        if (node.parentSlot === null && node.slot === 'tuning') {
+            const trulyTuning = [];
+            const misnested = [];
+            for (const child of node.children) {
+                if (child.parentSlot === 'tuning') trulyTuning.push(child);
+                else misnested.push(child);
+            }
+            topLevel.push({ ...node, children: trulyTuning });
+            topLevel.push(...misnested);
+        } else {
+            topLevel.push(node);
+        }
+    }
+
+    for (const node of topLevel) {
+        const fqSlot = node.parentSlot ? `${node.parentSlot}.${node.slot}` : node.slot;
+        switch (fqSlot) {
             case 'info':
                 score.info = { ...node.props };
                 break;
             case 'tuning':
                 score.tuning = buildTuning(node);
                 break;
-            case 'article':
-                score.articles.push(buildArticle(node));
+            case 'stage.cone':
+                score.stageCone = { type: 'stage_cone', ...node.props };
                 break;
-            case 'stage_voice':
+            case 'stage.voice':
                 score.stageVoices.push({
+                    type: 'stage_voice',
                     name: node.positionals[0],
                     direction: node.props.direction,
                     distance: node.props.distance,
@@ -148,7 +171,11 @@ export function buildModel(rawTree) {
                 score.bars.push(buildBar(node));
                 break;
             default:
-                score[node.slot] = buildGeneric(node);
+                if (node.parentSlot === 'articles') {
+                    score.articles.push(buildArticle(node));
+                } else {
+                    score[node.slot] = buildGeneric(node);
+                }
         }
     }
 
@@ -156,12 +183,17 @@ export function buildModel(rawTree) {
 }
 
 function buildTuning(node) {
-    const t = { base: node.props.base, scales: {}, chords: {} };
+    const t = { type: 'tuning', base: node.props.base, scales: {}, chords: {}, frequencyFactors: null };
     for (const child of node.children) {
         if (child.slot === 'scales') {
             t.scales[child.positionals[0]] = child.positionals.slice(1);
         } else if (child.slot === 'chords') {
             t.chords[child.positionals[0]] = child.positionals.slice(1);
+        } else if (child.slot === 'frequency_factors') {
+            t.frequencyFactors = {
+                label: child.props.label ?? null,
+                factors: child.positionals.slice(),
+            };
         }
     }
     return t;
@@ -170,11 +202,9 @@ function buildTuning(node) {
 function buildArticle(node) {
     return {
         type: 'article',
+        subtype: node.slot,
         name: node.positionals[0],
         props: { ...node.props },
-        properties: node.children
-            .filter(c => c.slot === 'property')
-            .map(c => ({ name: c.positionals[0], ...c.props })),
     };
 }