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/sources/249_Chinese-businessman.txt

@@ -71,6 +71,46 @@ The victim is reported to have received treatment at a private hospital in Narah
 
 The Police said he had filed an official complaint with the Colpetty Police last evening. Investigations are underway into the inciden
 
+------------------------------------------------------------------------------------------------
+FETCHED ARTICLE 1  [RAW EXTRACT — NOT YET TRIMMED]
+  !! This is the whole page as extracted. It still contains site furniture,
+  !! and may contain teaser headlines for UNRELATED cases. Trim on read-through.
+  !! Do not quote from it without checking the passage belongs to this case.
+  Source     newswire.lk
+  URL        https://www.newswire.lk/2025/08/25/chinese-group-kidnap-rob-fellow-businessman-in-colombo/
+  Field      url
+  Retrieved  2026-09-05T12:46:34+00:00 via raw HTTP retrieval, deterministic extraction (HTTP 200)
+  Language   unknown
+  Kept       paragraphs ALL 10 paragraphs, untrimmed
+  Length     1,033 chars
+  Integrity  sha256 9a96d17fdd37ebd1aa8139d91a52378b9473a2b55528ec0232ebcd5548ca6d98
+  Trimmed    NOT TRIMMED. Full page extract; trim on read-through.
+  Caveat     retrieved from a live page on the date above. Unlike text copied
+             from the spreadsheet, there is no second copy to hash it against.
+------------------------------------------------------------------------------------------------
+
+ORIGINAL (unknown, verbatim as retrieved)
+
+Chinese group kidnap & rob fellow businessman in Colombo - Newswire
+
+Chinese group kidnap & rob fellow businessman in Colombo
+
+A group of Chinese nationals residing in Sri Lanka have allegedly abducted a fellow Chinese businessman and robbed him of approximately USD 60,000.
+
+According to the Police, the victim, who operates a store on R.A. De Mel Mawatha in Colpetty, was abducted around 9:00 pm last Friday (22).
+
+He was reportedly taken away in a vehicle and held captive in a building for about a day.
+
+During his confinement, the suspects allegedly carried out the robbery by transferring the money online.
+
+The Police said the suspects had later abandoned him on a roadside on Saturday afternoon (23).
+
+The victim is reported to have received treatment at a private hospital in Narahenpita for injuries sustained during the abduction.
+
+The Police said he had filed an official complaint with the Colpetty Police last evening. Investigations are underway into the incident. (Newswire)
+
+© 2026 Wire Digital. All Rights Reserved.
+
 ================================================================================================
 generated from attacks-export-Gart-website.json + reported_K&R  |  case 249
 ================================================================================================