iOS: keep older build numbers when regenerating the source

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ios/scripts/make-source.py

@@ -19,7 +19,13 @@ def get(url):
 
 
 yml = open(os.path.join(HERE, "..", "project.yml")).read()
-builds = {}  # only the current build number is known locally; older ones fall back to the version
+# Build numbers: older ones from the last source.json, the current one from project.yml.
+builds = {}
+try:
+    for v in json.load(open(os.path.join(HERE, "..", "source.json")))["apps"][0]["versions"]:
+        builds[v["version"]] = v["buildVersion"]
+except (OSError, ValueError, KeyError, IndexError):
+    pass
 m = re.search(r'MARKETING_VERSION: "(.*)"', yml), re.search(r'CURRENT_PROJECT_VERSION: "(.*)"', yml)
 builds[m[0][1]] = m[1][1]