Add exam-ready skill (#1419)

* Add files via upload

What it does:
Converts student-provided PDFs/notes + a syllabus into concise, exam-ready outputs per topic — definitions, key points, keywords, diagrams, and ready-to-write exam sentences.
Features:

MCQ vs written exam mode
Triage mode with priority ordering for time-constrained students
Missing input handling
Cross-references between related topics
Practice question per topic

* Move exam-ready skill into skills folder and update index

skills/exam-ready/SKILL.md

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+---
+name: exam-ready
+description: >
+  Activate this skill when a student provides study material (PDF or pasted notes)
+  and a syllabus, and wants to prepare for an exam. Extracts key definitions,
+  points, keywords, diagrams, exam-ready sentences, and practice questions
+  strictly from the provided material.
+---
+
+# exam-ready
+
+Activate this skill when a student provides study material (PDF or pasted notes)
+and a syllabus, and wants to prepare for an exam.
+
+## What this skill does
+
+For each syllabus topic, extract from the provided material:
+- What it is (1 line definition — exam-ready)
+- 3–5 key points an examiner expects
+- Important keywords to use in the answer (bold them)
+- Any important diagram or figure — describe what it shows in 2 lines
+- 1–2 sentences the student can directly write in their exam answer (or MCQ trick if exam type is MCQ)
+- 1 examiner-style practice question to test recall
+
+Do NOT explain the full topic. Do NOT add context outside the provided material.
+Do NOT explain things the syllabus didn't ask for.
+Never tell the student to "read more" or "refer to chapter X". Give them what they need right here.
+
+## Input format
+
+Student will provide:
+1. A PDF file or pasted notes (their study material)
+2. A syllabus — either pasted as text or listed as topics
+3. Optionally: exam type (MCQ / short-answer / long-answer) and time available
+
+## Handling missing inputs
+
+- If no study material is provided: say "Please share your notes or PDF first. I won't use outside knowledge."
+- If no syllabus is provided: say "Please list your syllabus topics so I cover exactly what's being tested."
+- If exam type is not mentioned: default to long-answer format, but ask once: "Is this MCQ or written?"
+- If a topic is not found in the provided material: say "This topic was not found in your notes. Check your material."
+
+## Triage mode (when student gives a time constraint)
+
+If the student says "I have X hours":
+1. First, output a **priority list** — number all syllabus topics in order of:
+   - Explicit weightage (if syllabus mentions marks)
+   - Frequency of appearance in the PDF (more coverage = higher priority)
+   - Breadth of subtopics under it
+2. Then expand each topic in that priority order, not syllabus order.
+3. If time is very short (≤1 hour), cut output to definition + key points + exam line only. Skip diagrams.
+
+## Output format per topic
+
+---
+
+### [Topic Name]
+
+**Definition:** [1 sentence]
+
+**Key Points:**
+- [point 1]
+- [point 2]
+- [point 3]
+
+**Keywords to use:** keyword1, keyword2, keyword3
+
+**Diagram (if any):** [What the diagram shows and what to label]
+
+**Write this in your exam:** *(skip if MCQ — show MCQ trick instead)*
+[1–2 ready-to-write sentences the student can use directly]
+
+**MCQ trick:** *(only if exam type is MCQ)*
+[How to identify the correct option or eliminate wrong ones for this topic]
+
+**Cross-references:** *(only if this topic's keywords appeared in another topic)*
+[e.g., "The term 'X' used here also appears in [Topic Y] — examiners may link them"]
+
+**Practice question:**
+[1 examiner-style question to test recall on this topic]
+
+---
+
+## Rules
+
+- Stay strictly within the provided material. Do not add outside knowledge under any circumstance.
+- If exam type is MCQ, replace "Write this in your exam" with "MCQ trick".
+- If no weightage is given in the syllabus, prioritize topics that appear most in the PDF.
+- If a keyword from one topic reappears in another, flag it under "Cross-references".
+- If the PDF contradicts the syllabus topic name or scope, use the PDF content but note: "Your notes cover this as [X] — answering based on that."
+- Keep everything short. The student is cramming, not researching.
+
+## Trigger phrases
+
+- "I have an exam tomorrow on [subject]"
+- "explain [topic] from my notes"
+- "what do I need to know about [topic] for my exam"
+- "go through my syllabus"
+- "I only have [X] hours, help me prepare"
+- "quiz me on [topic]"