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/246/01_tribune-net-ph.txt

@@ -0,0 +1,17 @@
+Chinese national kidnapped at Parañaque resort | Daily Tribune
+
+Philippine National Police (PNP) chief Nicolas Torre III on Monday confirmed a kidnapping incident in Parañaque City involving Chinese nationals.
+
+In a press briefing, Torre said a 30-year-old Chinese national was rescued from a resort-casino in Parañaque on Aug. 2 after being abducted by four fellow Chinese nationals who had initially offered to help him send money to China.
+
+The victim had asked the suspects to assist in remitting PHP 150,000 for his mother’s medical treatment. He had already handed over PHP 100,000 and later agreed to meet them at the resort to complete the transaction.
+
+While in transit, the suspects allegedly handcuffed, blindfolded, and threatened the victim with a firearm. They demanded USD 50,000 (approximately PHP 2.8 million) for his release.
+
+The victim was able to convince the suspects to return his phone, which he used to contact another Chinese national, who then called 911.
+
+Parañaque City police, in coordination with the PNP Anti-Kidnapping Group, conducted the rescue operation.
+
+Upon arrival, police found five individuals with the victim. One of them, a woman, was later identified as another victim.
+
+She told police that she had known one of the suspects and had gone to the resort the same day to exchange money. Her cash was taken, and she was prevented from leaving.

merge-output/staging/246/index.json

@@ -0,0 +1,16 @@
+[
+  {
+    "case": 246,
+    "n": 1,
+    "field": "url",
+    "url": "https://tribune.net.ph/2025/08/04/chinese-national-kidnapped-at-para%C3%B1aque-resort",
+    "host": "tribune.net.ph",
+    "fetched_at": "2026-09-05T12:46:40+00:00",
+    "verdict": "FETCHED",
+    "method": "raw",
+    "http": 200,
+    "chars": 1385,
+    "sha256": "9b291e899805b0a60cff100bf29c93013d515b232650d29adde28462e4715210",
+    "final_url": null
+  }
+]