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/d9c172442b774ab9bd740f730d5458d9/_urls.json

@@ -0,0 +1,11 @@
+{
+  "detail_url": "https://oshwhub.com/Knight_Sin/abcd_copy_copy_copy_copy_copy",
+  "cover_url": "https://image.lceda.cn/pullimage/ZDwFwoCTQXaqPb9zWKAcMGQrrSHR23mnSBw2BOcX.jpeg",
+  "attachments": [
+    {
+      "name": "仿制ODrive双轴MINI FOC控制器@Mo.PcbDoc",
+      "url": "https://image.lceda.cn/attachments/2021/8/kM4W9unPZFUQEQikOIyt4NkcbQHHx5CkgjgzPlEM.",
+      "original_id": "6d9d9dd4c695436ab01289600b7cb679"
+    }
+  ]
+}

data/raw/oshwhub/d9c172442b774ab9bd740f730d5458d9/description.md

@@ -0,0 +1,9 @@
+# 【FOC】无刷电机驱动器ODrive AP1.0-DRV8303版
+
+【ART-Pi】无刷电机驱动器ODrive AP0.3的分支
+
+---
+- Source: https://oshwhub.com/Knight_Sin/abcd_copy_copy_copy_copy_copy
+- Author: 矛盾聚合体 (Knight_Sin)
+- License: GPL 3.0
+- Published: 2022-02-24T08:21:24.000Z

data/raw/oshwhub/d9c172442b774ab9bd740f730d5458d9/metadata.json

@@ -0,0 +1,50 @@
+{
+  "source": "oshwhub",
+  "source_url": "https://oshwhub.com/Knight_Sin/abcd_copy_copy_copy_copy_copy",
+  "project_id": "d9c172442b774ab9bd740f730d5458d9",
+  "title": "【FOC】无刷电机驱动器ODrive AP1.0-DRV8303版",
+  "description_short": "【ART-Pi】无刷电机驱动器ODrive AP0.3的分支",
+  "description_path": "description.md",
+  "author": {
+    "username": "Knight_Sin",
+    "display_name": "矛盾聚合体",
+    "user_id": "b2b6f77150214141b9e14701d6b5e346"
+  },
+  "license": "GPL 3.0",
+  "tags": [],
+  "created_at": "2021-06-01T13:06:05.000Z",
+  "updated_at": "2024-11-21T16:23:11.000Z",
+  "published_at": "2022-02-24T08:21:24.000Z",
+  "crawled_at": "2026-04-28T17:29:17.398067+00:00",
+  "metrics": {
+    "likes": 269,
+    "stars": 692,
+    "forks": 699,
+    "views": 90414,
+    "watch": 0,
+    "comments": 73
+  },
+  "cover": {
+    "url": "https://image.lceda.cn/pullimage/ZDwFwoCTQXaqPb9zWKAcMGQrrSHR23mnSBw2BOcX.jpeg",
+    "path": null
+  },
+  "files": [
+    {
+      "name": "仿制ODrive双轴MINI FOC控制器@Mo.PcbDoc",
+      "url": "https://image.lceda.cn/attachments/2021/8/kM4W9unPZFUQEQikOIyt4NkcbQHHx5CkgjgzPlEM.",
+      "original_id": "6d9d9dd4c695436ab01289600b7cb679",
+      "ext": null,
+      "mime": "application/octet-stream",
+      "size": 10282496,
+      "md5": "bd9b5b62acb5c68aed502c1c8e79dbcd"
+    }
+  ],
+  "raw_fields": {
+    "path": "Knight_Sin/abcd_copy_copy_copy_copy_copy",
+    "grade": 4,
+    "origin": "std",
+    "public": true,
+    "publish": true,
+    "skipped_files": []
+  }
+}