Update chapter 0 to the 2026-27 lecture 0 slides

[ethan42]

Lecture 0 of 2026-27 is out on the course site (assets/pdf/lec00.pdf, 28/09, 41 pages). Last year's deck had 36 pages. This PR brings chapter 0 and its slide questions in line with the new deck.

What changed in the slides → what changed in the guide

Slide (2026)	Change	Guide
p. 10	New grading: 50% Γραπτές + 20% Εργαστήριο + 15% Ασκήσεις + 15% Προφορικές (others 70/15/15). Πρόοδος on 7/12, with Γραπτές = max(Τελική, 0.7·Τελική + 0.3·Πρόοδος). The adjustment is now against Γραπτές. Homework is submitted online, no longer "optional".	§0.2, Κύρια σημεία 3, Συχνά λάθη, Ε0.10, new Ε0.11
p. 12 (new)	Can I use ChatGPT/Copilot/Claude for the homework? No (honor code)	§0.2, Κύρια σημεία 4, Συχνά λάθη, new question slides-lec00-ai-homework
p. 18–19 (new)	School Discord, DIT Coding Club	§0.2, Διάβασμα
p. 25 (new)	Algorithm vs program (Al-Khwarizmi)	§0.5, Ορολογία/glossary, new Ε0.12, new question slides-lec00-program-vs-algorithm
p. 30 (new)	«Αμφισημίες παντού»: Pythia's oracle, an AI agent that hacks Hugging Face for a test's answers	§0.6
p. 4, 5, 13, 14, 17, 37	Department distinctions instead of the QS claim, "2026", labs start the week of 5/10, laptop is optional, check the FAQ + Piazza, Sea online compiler, Piazza fall2026	§0.1, §0.2, §0.8, §0.10, Διάβασμα

Other changes

• Slide questions: they now point to the new deck, with page numbers remapped and years: [2025, 2026]. The 2026 deck adds pages, so the generated Α0.x labels shift (the question ids stay the same).
• Tooling: the manifest gets an optional per-lecture url for decks published outside the 2025 release. pdf-prep.py uses it. make fetch downloads the new deck to sources/slides/2026/.
• sources/extract/lec00.yaml: the outline is rewritten for 41 pages, and a changes_from_2025 list is added.
• README: one sentence noting that the guide is being updated with the 2026-27 decks as they come out.

Left alone, for later

• Chapter 4 / slides-lec04-grade-* use the 2025 grading formula as a programming exercise. They will be updated when the 2026 lecture 4 is out.
• The Kahoot results in chapter 0 are from 2025-26.

make check passes.

🤖 Generated with Claude Code