crawler: --no-cover, --concurrency, drop cross-host sleep + batch-50 Step 1 done

Three crawler ergonomics for batch operations:

--no-cover  Skip cover image download. For scan-only modes (license/meta
            scrape) this drops ~1.3s/project and avoids slow-CDN hangs.

--concurrency N  ThreadPoolExecutor wrapping the per-project loop. Default
                 1 = serial (current behavior). Anonymous endpoints tolerate
                 5+ comfortably; output uses a print lock for readable
                 interleaved progress. fetch_cover plumbs through crawl_one.

Drop cross-host sleep #1: in crawl_one between detail HTML (oshwhub.com)
and cover image (image.lceda.cn). Different hosts — sleep was unnecessary.
Saves ~1s/project. Sleep #2 (post-cover, before next iteration) stays — it
gates the next oshwhub.com hit.

download_to gains max_seconds wall budget (default 60s, cover uses 15s).
Defends against pathologically slow CDN connections — observed 10 KB/s
on image.lceda.cn for one project, would have hung 6+ min on a 3.6 MB
cover otherwise. httpx default timeout resets per chunk, so streaming
downloads need an external wall-clock guard.

batch-50 Step 1 (license/meta scrape) shipped:
  50/50 candidates have metadata.json + license recorded
  License distribution: GPL 3.0 32, Public Domain 6, NC variants 8,
                        CERN-OHL 1, MIT 1, CC BY 3.0 1
  Forge-friendly (non-NC): 41/50 (82%)
  Declared attachments: 180 files / 2.36 GB (median 18 MB/proj, max 304 MB)
  Walltime: 3min 26s for 28 projects at concurrency=5 (server-side
            HTML render bound, not sleep-bound)

One orphan partial cover (a670e60a...) cleaned up — leftover from the
first aborted run before the timeout fix landed.

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

data/raw/oshwhub/f643591fd411467db1e4efe3ce0970e8/_urls.json

@@ -0,0 +1,21 @@
+{
+  "detail_url": "https://oshwhub.com/mazhiliang/esp32-dev",
+  "cover_url": "https://image.lceda.cn/pullimage/XebSued0jf1SSfw4S0IaS83s1rhTo8pG3scKr3Qq.jpeg",
+  "attachments": [
+    {
+      "name": "esp32_test01.22.mp4",
+      "url": "https://image.lceda.cn/attachments/2022/1/9sXGJlNnVCjBDbrKQd6axcPqjMrRJ4f90qqAHc5w.mp4",
+      "original_id": "a4119ec8f09842a7a5b992ffc3746f71"
+    },
+    {
+      "name": "BOM_PCB_ESP32-DEV_rev0.html",
+      "url": "https://image.lceda.cn/attachments/2022/1/FwGlGNEdASYPZrScilVWYxQG1mFy8qxoNN1cQhLb.html",
+      "original_id": "668809a97eb3465c9c9245f78475535a"
+    },
+    {
+      "name": "Schematic_ESP32-IOT-KIT_2022-01-16.pdf",
+      "url": "https://image.lceda.cn/attachments/2022/1/4TRAS6KhQlDIz3Fwa4gd11HVYnNjlH76L8bqLLiY.pdf",
+      "original_id": "9f2ce6e8a51d42618461edd605867142"
+    }
+  ]
+}

data/raw/oshwhub/f643591fd411467db1e4efe3ce0970e8/description.md

@@ -0,0 +1,9 @@
+# ESP32开发板 ESP32-IOT-KIT全开源物联网开发板
+
+以ESP32模组为主控设计的开发板，支持WIFI、蓝牙、以太网、RS485、CAN等通信方式。软硬件全开源计划，配套Easyio驱动库、CSDN博文教程，方便大家从ESP-IDF入门物联网的学习与开发
+
+---
+- Source: https://oshwhub.com/mazhiliang/esp32-dev
+- Author: mazhiliang (mazhiliang)
+- License: Public Domain
+- Published: 2022-07-19T05:51:54.000Z

data/raw/oshwhub/f643591fd411467db1e4efe3ce0970e8/metadata.json

@@ -0,0 +1,68 @@
+{
+  "source": "oshwhub",
+  "source_url": "https://oshwhub.com/mazhiliang/esp32-dev",
+  "project_id": "f643591fd411467db1e4efe3ce0970e8",
+  "title": "ESP32开发板 ESP32-IOT-KIT全开源物联网开发板",
+  "description_short": "以ESP32模组为主控设计的开发板，支持WIFI、蓝牙、以太网、RS485、CAN等通信方式。软硬件全开源计划，配套Easyio驱动库、CSDN博文教程，方便大家从ESP-IDF入门物联网的学习与开发",
+  "description_path": "description.md",
+  "author": {
+    "username": "mazhiliang",
+    "display_name": "mazhiliang",
+    "user_id": "16e40f5e8057450ebcf365711ae72b64"
+  },
+  "license": "Public Domain",
+  "tags": [],
+  "created_at": "2021-09-21T02:34:42.000Z",
+  "updated_at": "2026-01-20T06:53:15.000Z",
+  "published_at": "2022-07-19T05:51:54.000Z",
+  "crawled_at": "2026-04-28T17:27:43.935462+00:00",
+  "metrics": {
+    "likes": 506,
+    "stars": 1072,
+    "forks": 719,
+    "views": 102935,
+    "watch": 0,
+    "comments": 145
+  },
+  "cover": {
+    "url": "https://image.lceda.cn/pullimage/XebSued0jf1SSfw4S0IaS83s1rhTo8pG3scKr3Qq.jpeg",
+    "path": null
+  },
+  "files": [
+    {
+      "name": "esp32_test01.22.mp4",
+      "url": "https://image.lceda.cn/attachments/2022/1/9sXGJlNnVCjBDbrKQd6axcPqjMrRJ4f90qqAHc5w.mp4",
+      "original_id": "a4119ec8f09842a7a5b992ffc3746f71",
+      "ext": "mp4",
+      "mime": "video/mp4",
+      "size": 1768026,
+      "md5": "d7cb1bec42772c7c21fbe4f1a1f69901"
+    },
+    {
+      "name": "BOM_PCB_ESP32-DEV_rev0.html",
+      "url": "https://image.lceda.cn/attachments/2022/1/FwGlGNEdASYPZrScilVWYxQG1mFy8qxoNN1cQhLb.html",
+      "original_id": "668809a97eb3465c9c9245f78475535a",
+      "ext": "html",
+      "mime": "text/html",
+      "size": 1459293,
+      "md5": "8ce96ca05237a6c6cf533d2eb8874fdf"
+    },
+    {
+      "name": "Schematic_ESP32-IOT-KIT_2022-01-16.pdf",
+      "url": "https://image.lceda.cn/attachments/2022/1/4TRAS6KhQlDIz3Fwa4gd11HVYnNjlH76L8bqLLiY.pdf",
+      "original_id": "9f2ce6e8a51d42618461edd605867142",
+      "ext": "pdf",
+      "mime": "application/pdf",
+      "size": 474099,
+      "md5": "8c0c8eb078fe6982ee450d838e2097f4"
+    }
+  ],
+  "raw_fields": {
+    "path": "mazhiliang/esp32-dev",
+    "grade": 3,
+    "origin": "std",
+    "public": true,
+    "publish": true,
+    "skipped_files": []
+  }
+}