content audit sec01-06: fixes (audit_content.py + 12 file/card corrections)

- tools/audit_content.py: per-file vs item-title triage (SUSPECT/SMALL/NO-TEXT/NO-CYR)
- sec01: .part removed; 10 files restored .pdf ext (LFS rename); #04/#19/#27 verify notes
- sec02 #16: corrupted double-encoded txt -> clean flib fb2 b/844509; #17/#22 doc verified via catdoc
- sec03 #11: -b epub = Spanish von Franz (Paidós 1983, forged EN OPF) -> bonus label
- sec03 #42: КАРО 2012 'Irish Tales' = EN reader (not RU, not the listed book) -> bonus rename
- sec03 #56: Onians b/c/d/e = Cambridge 24-87KB previews -> labeled
- sec06 #18: filename 1981->1989 (Perera 'Descent to the Goddess' 1989; 1981 = other book)
- sec06 #28: ia Zimmer OCR layer = foreign Devanagari text; images = RKP (p.100 verified)
- sec04 #30: buksmart 2020 = RU/FR bilingual w/ VeryPDF watermarks -> note
- linter: azw3/mobi ext + underscore in fname regex; manifest cross-check ignores off-disk rows;
  8 legacy cards section-order fixed (CR before DL)
- AGENTS.md: 'Content audit (2026-09-25)' lessons section
- check-md: 0/219

downloads/04-pictures/MANIFEST.md

@@ -74,7 +74,7 @@
 |---|---|---|---|
 | 30-kandinsky-spiritual-ru-arhimed-1992.pdf | 2 MB | lg f/3418650 | scanned, rendered p1 ✓ |
 | 30-kandinsky-spiritual-en-floating-press-2008.pdf | 554 KB | lg f/91677950 | pdftext: Sadler tr., Floating Press 2008, complete (ends w/ Dalcroze passage) ✓ |
-| 30-kandinsky-spiritual-ru-buksmart-2020-t1.pdf | 146 MB | lg f/94051405 | trailer intact ✓ |
+| 30-kandinsky-spiritual-ru-buksmart-2020-t1.pdf | 146 MB | lg f/94051405 | trailer intact ✓; VeryPDF-водяные знаки (audit 2026-09-25) |
 | 30-kandinsky-spiritual-ru-buksmart-2020-t2.pdf | 154 MB | lg f/94051663 | trailer intact ✓ |
 
 ### 31 — The Tree Test — 1 file — 1 file (flagged), EN absent