feat(sources): fetch linked URLs for the 252 spreadsheet-only cases

Until now only cases 357+ (plus a few older ones) had their linked URLs
fetched; the other 252 dossiers held just the text pasted into the
spreadsheet, often only the lede. This pass fetches every linked URL for
those cases so the full text is on file before link rot takes it.

- stage_all.py: new --include-sheet-cases flag that lifts the skip on
  cases holding spreadsheet articles. Resumable as before.
- staging/: raw extracts and index.json for the 252 cases.
- sourced-articles.json, case-files-manifest.json: 188 new UNTRIMMED
  blocks. 179 cases gained at least one fetched article; 73 got none
  (49 BLOCKED, 18 THIN, 9 DEAD, 4 video/social, 3 ERROR).
- sources/*.txt: rebuilt with build_cases.py --all. Sheet pastes are
  kept; fetched blocks sit beside them under the NOT YET TRIMMED banner.
  Files previously committed with CRLF are now LF.
- wayback-availability.json: Wayback snapshots exist for 73 of the 98
  failed URL slots; input for an archive-fetch pass.
- README-START-HERE.md: progress note and next step.

verify_all.py PASSES (1836 checks).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GZZENdTLzNGsbNy4DyF1yt

merge-output/staging/094/01_scmp-com.txt

@@ -0,0 +1,19 @@
+Bitcoin trader robbed of HK$3 million in cash when ‘sellers’ in Hong Kong show up with knife | South China Morning Post
+
+Bitcoin trader robbed of HK$3 million in cash when ‘sellers’ in Hong Kong show up with knife
+
+The 39-year-old trader from South Korea arrived for the exchange on Ashley Road in Tsim Sha Tsui
+
+Armed gang snatches bag of cash he is carrying, cuts victim’s hand and then flees
+
+Published: 11:09pm, 28 Jul 2021Updated: 3:18am, 29 Jul 2021
+
+A cryptocurrency trader was robbed of more than HK$3 million (US$128,500) in cash at knifepoint when he went to meet a bitcoin seller in Hong Kong on Wednesday afternoon.
+
+The 39-year-old trader from South Korea arrived at Astoria Building on Ashley Road in Tsim Sha Tsui for the exchange at about 6.20pm. He was approached by four men, one of whom attacked him with the knife.
+
+The criminals snatched a bag he was carrying with about HK$3.29 million inside and fled. The trader asked a friend to call police and officers searched the area but failed to locate the suspects.
+
+The victim suffered a cut to his hand and was sent to hospital for treatment. Detectives from the Yau Tsim district crime squad are investigating.
+
+Several robberies involving digital currency have taken place in Hong Kong this year. In June, a 22-year-old cryptocurrency trader was sprayed in his eyes with an unknown substance and robbed of HK$2 million while on his way to buy the digital money in Kwun Tong. Three men and a woman were later arrested.

merge-output/staging/094/index.json

@@ -0,0 +1,16 @@
+[
+  {
+    "case": 94,
+    "n": 1,
+    "field": "url",
+    "url": "https://www.scmp.com/news/hong-kong/law-and-crime/article/3142919/bitcoin-trader-robbed-hk3-million-cash-when-sellers",
+    "host": "scmp.com",
+    "fetched_at": "2026-09-05T12:53:27+00:00",
+    "verdict": "FETCHED",
+    "method": "raw",
+    "http": 200,
+    "chars": 1487,
+    "sha256": "db1581127b1a9721437fab8f3ead39d363f9dd28cfeea1daa0f5790b58f40d06",
+    "final_url": null
+  }
+]