Add persian-tutor: Gradio-based GCSE Persian language learning app

Vocabulary study with FSRS spaced repetition, AI tutoring (Ollama/Claude),
essay marking, idioms browser, Anki export, and dashboard. 918 vocabulary
entries across 39 categories. 41 tests passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

python/persian-tutor/modules/tutor.py

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+"""Conversational Persian lessons by GCSE theme."""
+
+import time
+
+import db
+from ai import chat_ollama
+
+TUTOR_SYSTEM_PROMPT = """You are a friendly Persian (Farsi) language tutor teaching English-speaking GCSE students.
+
+Rules:
+- Use a mix of English and Persian. Start mostly in English, gradually introducing more Persian.
+- When you write Persian, also provide the Finglish transliteration in parentheses.
+- Keep responses concise (2-4 sentences per turn).
+- Ask the student to practice: translate phrases, answer questions in Persian, or fill in blanks.
+- Correct mistakes gently and explain why.
+- Stay on the current theme/topic.
+- Use Iranian Persian (Farsi), not Dari or Tajik.
+- Adapt to the student's level based on their responses."""
+
+THEME_PROMPTS = {
+    "Identity and culture": "Let's practice talking about family, personality, daily routines, and Persian celebrations like Nowruz!",
+    "Local area and environment": "Let's practice talking about your home, neighbourhood, shopping, and the environment!",
+    "School and work": "Let's practice talking about school subjects, school life, jobs, and future plans!",
+    "Travel and tourism": "Let's practice talking about transport, directions, holidays, hotels, and restaurants!",
+    "International and global dimension": "Let's practice talking about health, global issues, technology, and social media!",
+    "Free conversation": "Let's have a free conversation in Persian! I'll help you along the way.",
+}
+
+
+def start_lesson(theme):
+    """Generate the opening message for a new lesson.
+
+    Returns:
+        (assistant_message, messages_list)
+    """
+    intro = THEME_PROMPTS.get(theme, THEME_PROMPTS["Free conversation"])
+    system = TUTOR_SYSTEM_PROMPT + f"\n\nCurrent topic: {theme}. {intro}"
+
+    messages = [{"role": "user", "content": f"I'd like to practice Persian. Today's theme is: {theme}"}]
+    response = chat_ollama(messages, system=system)
+    messages.append({"role": "assistant", "content": response})
+
+    return response, messages, system
+
+
+def process_response(user_input, messages, system=None):
+    """Add user input to conversation, get AI response.
+
+    Returns:
+        (assistant_response, updated_messages)
+    """
+    if not user_input or not user_input.strip():
+        return "", messages
+
+    messages.append({"role": "user", "content": user_input.strip()})
+    response = chat_ollama(messages, system=system)
+    messages.append({"role": "assistant", "content": response})
+
+    return response, messages
+
+
+def save_session(theme, messages, start_time):
+    """Save the current tutor session to the database."""
+    duration = int(time.time() - start_time)
+    db.save_tutor_session(theme, messages, duration)