Replace the sample data with synthetic fixtures and regenerate goldens and thumbnails

The template harness, tests and thumbnails now use a neutral vendor, bank account and
a generated sample wordmark (scripts/logo/make-sample-logo.mjs). Layout goldens and the
14 picker thumbnails are regenerated. Fixture strings keep their original lengths where
layout tests depend on them.

src/pdf/testing/goldens.json

@@ -1,23 +1,23 @@
 {
   "classic-a4-tax-3": {
     "pages": 1,
-    "fingerprint": "35b03b20aeec3dcbb808300b6e8f0b1867dfd69d5fd6f69aaee891c354955092",
+    "fingerprint": "87b12a5c1b1a9b45ac6a8fd5862c8e7b5de8d203731fe4e485872dea5bbb07cd",
     "invoiceNumber": "ST/2026-001",
     "totalText": "₹8,625.80",
     "pageLabel": "Page 1 of 1",
     "textHashes": [
-      "855dd2d104e80ff599210d69f643be0ccb281e6583cbcea2dafa5fdcb09f03fc"
+      "ddda2419b84480c00d8ed76088898277711f448ef11c2383a48494ecd0e4c524"
     ],
     "firstPageText": "Selftest Studio 1 Test Lane, Test Town, Bangalore - 560005 selftest@example.com 9000000000 PAN: AAAAA0000A GSTIN: 29AAAAA0000A1Z5 TAX INVOICE Invoice No. ST/2026-001 Date 15 Sept 2026 Due Date 15 Oct 2026 B I L L E D T O Acme Learning Pvt Ltd 42 MG Road Bangalore 560001 GSTIN: 29ABCDE1234F1Z5 Place of Supply: 29 – Karnataka S . N O D E S C R I P TI O N H S N /S AC U N IT P R I C E QT Y A M O U N T 1 Voice-over session 1 - narration for module 1 998397 ₹1,200.00 per hour 1 ₹1,200.00 2 Voice-over session 2 - narration for module 2 998397 — 1 ₹2,510.00 3 Voice-over session 3 - narration for module 3 998397 ₹1,200.00 per hour 3 ₹3,600.00 Subtotal ₹7,310.00 Taxable value ₹7,310.00 CGST (9%) ₹657.90 SGST (9%) ₹657.90 Total ₹8,625.80 Amount in words: Indian Rupees Eight Thousand Six Hundred Twenty Five and Eighty Paise Only Tax is payable on reverse charge: No PAY T O Selftest Studio State Bank of India Account No.: 00000000000 Branch: 000000 IFSC: SBIN0000000 Selftest Studio Proprietor Computer-generated invoice; no signature is required. Selftest Studio Generated with Voiced — a Bongbetic product Page 1 of 1"
   },
   "classic-letter-unreg-60": {
     "pages": 3,
-    "fingerprint": "78d60e1b72dac0e40fea96cbf34c35cfeb637dbe0bc9754dcecba72231197e75",
+    "fingerprint": "6999be0875f78e2c87aee1fd0ffa1dfe651faa7a7c0a9b4c2f78c1bdff53c7d4",
     "invoiceNumber": "ST/2026-002",
     "totalText": "₹1,56,000.00",
     "pageLabel": "Page 1 of 3",
     "textHashes": [
-      "1728b53a177e385584d2dc33b2e71607f860886632f32a5911364f86f345c950",
+      "4a0cf8a7c1565037edd4d9941251e030fd9e6fca25845b971465e5cf9d916936",
       "870e9a70c0546550d002e5eb5728f342b1d235094c6b645ddda68a6306b33f7b",
       "fca30345bc73289cdcad200f888f917ff9a5386cdd64e41ea7dccc64f2b7e5e0"
     ],