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/201/01_vrt-be.txt

@@ -0,0 +1,17 @@
+Failed kidnap attempt victim was Bitcoin millionaire’s wife (VIDEO) | VRT NWS: news
+
+Failed kidnap attempt victim was Bitcoin millionaire’s wife (VIDEO)
+
+The identity has been revealed of the person, who was the subject of an attempted kidnap in Brussels last Friday. The abduction led to a police chase that ended in a crash in Bruges and the arrest of suspects. The victim, who was injured in the crash, has been identified as the wife of a ‘crypto-influencer’. Her husband had been keen to post on social media that he had become a millionaire by investing in crypto currencies. It’s thought his wife was possibly kidnapped to obtain ransom money.
+
+The Brussels public prosecutor's office has now revealed that a minor was among the would-be kidnappers.
+
+A youth magistrate now holds jurisdiction over the boy, who has been placed in a closed juvenile institution. The 3 other suspects in the case are aged 18 or more and have been detained by the investigating judge.
+
+The victim of the failed abduction is the wife of a well-known ‘crypto-influencer’. That is someone who regularly posts on social media about his investments in crypto currencies like bitcoin.
+
+A few weeks ago the influencer posted that his crypto wallet was now worth €1.6 million. He claimed he bought bitcoins back in 2011, when they were worth less than 2 euros each.
+
+‘In 2011 bitcoins were only circulating in a small circle of people. I don't know if his story is true,’ says Thomas Spaas, a lawyer who assists crypto investors. To collect a fortune, you just had to keep the bitcoins,’ the lawyer says. In 2011 you could buy a bitcoin for less than 2 euros. Today the price for one bitcoin hovers around 100,000 euros.
+
+The value of bitcoin skyrocketed last week, breaking record after record. Spaas says he believes in the technology but seems to imply that it is not wise to publicise your crypto currency's profits.

merge-output/staging/201/index.json

@@ -0,0 +1,16 @@
+[
+  {
+    "case": 201,
+    "n": 1,
+    "field": "url",
+    "url": "https://www.vrt.be/vrtnws/en/2024/12/24/failed-kidnap-attempt-victim-was-bitcoin-millionaires-wife/",
+    "host": "vrt.be",
+    "fetched_at": "2026-09-05T12:49:31+00:00",
+    "verdict": "FETCHED",
+    "method": "raw",
+    "http": 200,
+    "chars": 1899,
+    "sha256": "f6b70e6e2cad506ec7a735ffd5c7357c497c582651221ff8eedcb19d901f3ab4",
+    "final_url": null
+  }
+]