Article export + Bootstrap toggle + export change log

- patchScore() now accepts articles[] and returns { text, log } instead
  of a plain string. Dirty articles are re-serialized into the articles:
  block (block style, replacing any existing flow-style entries). Clean
  articles bypass the patcher entirely.
- article.isDirty is set on direct property edits so the exporter can
  distinguish directly changed entities from propagated dirty state.
- patchScore() log collects { level:'changed', path } for each patched
  article/instrument/bar, and a { level:'info', message } entry for the
  count of bar documents passed through unchanged.
- CP pane shows the export log above the status poller after each export.
- Article scope toggle replaced with Bootstrap form-check form-switch;
  hand-rolled .se-toggle CSS removed.
- Test suite updated for { text, log } return; 11 new assertions (188 total).

static/components/PaneCP.js

@@ -67,7 +67,11 @@ export const PaneCP = {
             try {
                 const raw = await fetchScoreText(props.store.credentials);
                 props.store.rawScoreText = raw;
-                const patched = patchScore(raw, props.store.scoreModel.instruments, props.store.scoreModel.bars, props.store.scoreModel.info);
+                const model = props.store.scoreModel;
+                const { text: patched, log } = patchScore(
+                    raw, model.instruments, model.bars, model.info, model.articles ?? [],
+                );
+                props.store.exportLog = log;
                 await putScoreText(patched, props.store.credentials);
                 props.store.synthesisStatus = { frozen: false, currently_rendered_notes: 0, notes_in_total: 0 };
             } catch (e) {
@@ -134,6 +138,18 @@ export const PaneCP = {
                 // Export error
                 exportError.value ? h('div', { class: 'se-error' }, exportError.value) : null,
 
+                // Export log (shown after export, cleared on next import)
+                store.exportLog?.length
+                    ? h('div', { class: 'se-export-log' },
+                        store.exportLog.map((entry, i) =>
+                            h('div', {
+                                key: i,
+                                class: entry.level === 'changed' ? 'se-export-changed' : 'se-export-info',
+                            }, entry.path ? `→ ${entry.path}` : entry.message)
+                        )
+                      )
+                    : null,
+
                 // Status poller (while running)
                 store.synthesisStatus && !store.synthesisStatus.frozen
                     ? h(StatusPoller, { store }) : null,