[ethan42]

Same as #3 and #5: chapter 4, its slide questions, sources/extract/lec04.yaml, the manifest, the README and make fetch now point to the 2026-27 deck (https://progintro.github.io/assets/pdf/lec04.pdf).

What changed in the deck (page-by-page comparison with 2025-26): 36 pages instead of 44.

• Moved: pair programming (2025 pp. 5–7) is now in lecture 3 (2026 pp. 38–40).
• Removed:
  • the grade program with argc/argv/atoi and the «Κανόνας Αναπροσαρμογής» exercise (2025 pp. 8–10). The program is still revisited on 2026 p. 30.
  • the two bitwise quiz slides, MSB and 0xbeef | 0xcafe0000 (2025 pp. 29–30)
• Small changes: the title drops «Live Coding», announcements are N/A, and the clone example is hw0-2026-barbouni-2005 and points to Φυλλάδιο 0.
• Page mapping: 2025 pp. 11–28 → 2026 pp. 5–22, and 2025 pp. 31–44 → 2026 pp. 23–36.

How the guide handles it:

• The chapter keeps the removed material. It's still correct and useful, and the reading list says where each part is: the 2026 deck, lecture 3 for pair programming, or the 2025 deck for the grade program and the bitwise questions.
• Six slide questions move to the new deck with their new page numbers.
• Four questions come from removed slides (grade-program, grade-adjustment, msb, cafebeef). They keep citing the 2025-26 deck, and their source now reads «Διάλεξη 4 (2025-26)», so «διαφάνεια 30» isn't mistaken for the new p. 30. I gave slides-lec03-power-outage the same label.

If you'd rather drop the removed material from chapter 4, or move the pair-programming part to chapter 3, that's a follow-up.

make check passes and the generated lists are up to date.

Opened from socrates.