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/d53cd4f3355c45319a36b19cc9ff252e/_urls.json

@@ -0,0 +1,16 @@
+{
+  "detail_url": "https://oshwhub.com/zl4430/mpu-6500-280",
+  "cover_url": "https://image.lceda.cn/pullimage/kVn5PSaVguqoyJHRLrVBiqmm9y9mohfjeUNv97so.jpeg",
+  "attachments": [
+    {
+      "name": "左手边 F405 MPU 6500 试飞成功 部分功能待测试版 (2).zip",
+      "url": "https://image.lceda.cn/attachments/2021/12/OSfnDfGqKVQlgJLVankEWRB2ja0WbZFqrNvHxWGQ.zip",
+      "original_id": "f312429674e245208262d1e1b7b5c87c"
+    },
+    {
+      "name": "F405+6500陀螺仪飞控 20 30双版本含固件和配置文件左手边.zip",
+      "url": "https://image.lceda.cn/attachments/2022/4/IVajraS7oaHGtqfjVGjkgRXsVtTU5KJJFW9BRYiN.zip",
+      "original_id": "20601577108b423b8cb3c4971d93ee81"
+    }
+  ]
+}

data/raw/oshwhub/d53cd4f3355c45319a36b19cc9ff252e/description.md

@@ -0,0 +1,9 @@
+# STM F405飞控 bf inav  穿越机 固定翼飞控
+
+F405飞控，MPU6500陀螺仪，低成本。20、30孔双版本。PCB文件在附件，bf、inav地面站接USB线刷固件。自动返航测试视频https://b23.tv/GcbdOsY
+
+---
+- Source: https://oshwhub.com/zl4430/mpu-6500-280
+- Author: 左手DIY (zl4430)
+- License: Public Domain
+- Published: 2023-11-13T08:19:05.000Z

data/raw/oshwhub/d53cd4f3355c45319a36b19cc9ff252e/metadata.json

@@ -0,0 +1,59 @@
+{
+  "source": "oshwhub",
+  "source_url": "https://oshwhub.com/zl4430/mpu-6500-280",
+  "project_id": "d53cd4f3355c45319a36b19cc9ff252e",
+  "title": "STM F405飞控 bf inav  穿越机 固定翼飞控",
+  "description_short": "F405飞控，MPU6500陀螺仪，低成本。20、30孔双版本。PCB文件在附件，bf、inav地面站接USB线刷固件。自动返航测试视频https://b23.tv/GcbdOsY",
+  "description_path": "description.md",
+  "author": {
+    "username": "zl4430",
+    "display_name": "左手DIY",
+    "user_id": "de62e47bf33f45158f4fc792835838eb"
+  },
+  "license": "Public Domain",
+  "tags": [],
+  "created_at": "2021-11-24T03:06:48.000Z",
+  "updated_at": "2025-12-19T00:37:21.000Z",
+  "published_at": "2023-11-13T08:19:05.000Z",
+  "crawled_at": "2026-04-28T17:29:23.196172+00:00",
+  "metrics": {
+    "likes": 373,
+    "stars": 799,
+    "forks": 281,
+    "views": 103656,
+    "watch": 0,
+    "comments": 173
+  },
+  "cover": {
+    "url": "https://image.lceda.cn/pullimage/kVn5PSaVguqoyJHRLrVBiqmm9y9mohfjeUNv97so.jpeg",
+    "path": null
+  },
+  "files": [
+    {
+      "name": "左手边 F405 MPU 6500 试飞成功 部分功能待测试版 (2).zip",
+      "url": "https://image.lceda.cn/attachments/2021/12/OSfnDfGqKVQlgJLVankEWRB2ja0WbZFqrNvHxWGQ.zip",
+      "original_id": "f312429674e245208262d1e1b7b5c87c",
+      "ext": "zip",
+      "mime": "application/x-zip-compressed",
+      "size": 3364791,
+      "md5": "53d488d3fbf10b6f9327cf9b65a01ced"
+    },
+    {
+      "name": "F405+6500陀螺仪飞控 20 30双版本含固件和配置文件左手边.zip",
+      "url": "https://image.lceda.cn/attachments/2022/4/IVajraS7oaHGtqfjVGjkgRXsVtTU5KJJFW9BRYiN.zip",
+      "original_id": "20601577108b423b8cb3c4971d93ee81",
+      "ext": "zip",
+      "mime": "application/x-zip-compressed",
+      "size": 9862164,
+      "md5": "e3666a7872adb6e693eeb2badec05074"
+    }
+  ],
+  "raw_fields": {
+    "path": "zl4430/mpu-6500-280",
+    "grade": 4,
+    "origin": "std",
+    "public": true,
+    "publish": true,
+    "skipped_files": []
+  }
+}