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/077/01_scmp-com.txt

@@ -0,0 +1,21 @@
+Gang snatches HK$3.5 million from Hong Kong cryptocurrency trader at knifepoint after she transfers digital tokens to ‘buyer’ | South China Morning Post
+
+Gang snatches HK$3.5 million from Hong Kong cryptocurrency trader at knifepoint after she transfers digital tokens to ‘buyer’
+
+Woman was paid HK$3.5 million in cash after using her iPhone to complete an online transaction to sell USDT tokens, police source says
+
+Three men then rushed from a room, and grabbed the money and iPhone before locking her in office
+
+Published: 12:52am, 19 Jan 2021Updated: 3:37am, 19 Jan 2021
+
+Hong Kong police are hunting for a gang of thieves who lured a female cryptocurrency trader to an office for a deal and robbed her of HK$3.5 million (US$448,700) in cash at knifepoint on Monday afternoon.
+
+The robbery – the second such hold-up in two weeks – took place at the Ricky Centre on Chong Yip Street in Kwun Tong around 2.30pm, after the woman met a man posing as a buyer.
+
+She had recently sold the man digital money in three transactions, each involving HK$600,000 to HK$700,000, according to police.
+
+“Investigations showed she was paid HK$3.5 million in cash after using her iPhone to complete an online transaction and sell him USDT tokens,” a police source said, referring to a type of cryptocurrency.
+
+“Soon after she was handed the money, three men carrying either a knife or a rod rushed out from a room and snatched the money and the iPhone from her at knifepoint.”
+
+He said the four fled after locking the victim in the office. The source said the gang could have carried out the earlier deals to win her trust and pave the way for the hold-up.

merge-output/staging/077/index.json

@@ -0,0 +1,16 @@
+[
+  {
+    "case": 77,
+    "n": 1,
+    "field": "url",
+    "url": "https://www.scmp.com/news/hong-kong/law-and-crime/article/3118249/gang-snatches-hk35-million-hong-kong-cryptocurrency",
+    "host": "scmp.com",
+    "fetched_at": "2026-09-05T12:54:12+00:00",
+    "verdict": "FETCHED",
+    "method": "raw",
+    "http": 200,
+    "chars": 1641,
+    "sha256": "279a1011a2f74e2727eb2fa3d1b6357f02a3c1e2eb3a5b6f4b5b9b156843eede",
+    "final_url": null
+  }
+]