batch-50: Step 3-4 source download from Guangzhou — 49/50 ok

Run on dev1 (Guangzhou) for the latency advantage. Walltime 3:41 vs
Singapore-estimated 1-2h (~30x speedup, mostly from image.lceda.cn
RTT going from 263ms to 2.6ms).

Pro 25:  24 ok + 1 fail (Super Dial 7f7565ef11 — Pro 2.x legacy
                          schematic/lists 401, separate cookie-perm issue)
         611 docs, 31 MB total
Std 25:  25 ok, 97 docs, 74 MB total
Combined: 49/50 success, 708 docs, 105 MB new disk usage

--max-source-mb 200 cap was not tripped; the 25 Pro candidates are all
under 10 MB, so the 481 MB X86-board outlier from the original sample
was not representative.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

data/raw/oshwhub/8624bf3d43ba4732bb256c08aafe186b/metadata.json

@@ -36,5 +36,23 @@
     "public": true,
     "publish": true,
     "skipped_files": []
-  }
+  },
+  "source_format": "easyeda-pro-legacy",
+  "source_path": "source/",
+  "source_documents": [
+    {
+      "doc_uuid": "c0f6316a981d43ba9ee2fb3583ec15c1",
+      "docType": 1,
+      "path": "source/c0f6316a981d43ba9ee2fb3583ec15c1.json",
+      "size": 79204,
+      "sha256": "9004416b6f35b69a49fbe833c97deab4de5b86ed4d492d0587f18d98f06d0a97"
+    },
+    {
+      "doc_uuid": "5bff943b3fc4443f894cb3ea0447e7f6",
+      "docType": 3,
+      "path": "source/pcb_5bff943b3fc4443f894cb3ea0447e7f6.json",
+      "size": 170046,
+      "sha256": "5742e2e6f28f36856db8a29112abb29c7011109745ceb66e48381fbfb700eeb5"
+    }
+  ]
 }