fix(pdf-server): rebase annotations baseline after save

After a successful save_pdf, update pdfBaselineAnnotations and
pdfBaselineFormValues to reflect what was written to disk. Without
this, removing all annotations after a save produced an empty diff
(compared to the stale pre-save baseline), incorrectly disabling
the save button even though the file on disk still had annotations.

Author: ochafik

examples/pdf-server/src/mcp-app.ts

@@ -3729,6 +3729,14 @@ async function savePdf(): Promise<void> {
       const sc = result.structuredContent as { mtimeMs?: number } | undefined;
       lastSavedMtime = sc?.mtimeMs ?? null;
 
+      // Rebase: the file on disk now contains our annotations + form values.
+      // Update the baseline so future diffs are relative to what was saved.
+      pdfBaselineAnnotations = [...annotationMap.values()].map((t) => ({
+        ...t.def,
+      }));
+      pdfBaselineFormValues.clear();
+      for (const [k, v] of formFieldValues) pdfBaselineFormValues.set(k, v);
+
       setDirty(false); // → updateSaveBtn() disables button
       const key = annotationStorageKey();
       if (key) {