Add Phases 3.2-4.3: STT, stories, syllables, gamification

Phase 3.2 — MicrophoneInput.tsx: Browser Web Speech API for
speech-to-text recognition (EN+DE), integrated for pronunciation practice.

Phase 4.1 — Story Generator: LLM-powered mini-stories using vocabulary
words, with highlighted vocab in HTML output. Backend endpoint
POST /learning-units/{id}/generate-story + frontend /learn/[unitId]/story.

Phase 4.2 — SyllableBow.tsx: SVG arc component for syllable visualization
under words, clickable for per-syllable TTS.

Phase 4.3 — Gamification system:
- CoinAnimation.tsx: Floating coin rewards with accumulator
- CrownBadge.tsx: Crown/medal display for milestones
- ProgressRing.tsx: Circular progress indicator
- progress_api.py: Backend tracking coins, crowns, streaks per unit

Also adds "Geschichte" exercise type button to UnitCard.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend-lehrer/progress_api.py

@@ -0,0 +1,131 @@
+"""
+Progress API — Tracks student learning progress per unit.
+
+Stores coins, crowns, streak data, and exercise completion stats.
+Uses JSON file storage (same pattern as learning_units.py).
+"""
+
+import os
+import json
+import logging
+from datetime import datetime, date
+from typing import Dict, Any, Optional, List
+from pathlib import Path
+
+from fastapi import APIRouter, HTTPException
+from pydantic import BaseModel
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(
+    prefix="/progress",
+    tags=["progress"],
+)
+
+PROGRESS_DIR = os.path.expanduser("~/Arbeitsblaetter/Lerneinheiten/progress")
+
+
+def _ensure_dir():
+    os.makedirs(PROGRESS_DIR, exist_ok=True)
+
+
+def _progress_path(unit_id: str) -> Path:
+    return Path(PROGRESS_DIR) / f"{unit_id}.json"
+
+
+def _load_progress(unit_id: str) -> Dict[str, Any]:
+    path = _progress_path(unit_id)
+    if path.exists():
+        with open(path, "r", encoding="utf-8") as f:
+            return json.load(f)
+    return {
+        "unit_id": unit_id,
+        "coins": 0,
+        "crowns": 0,
+        "streak_days": 0,
+        "last_activity": None,
+        "exercises": {
+            "flashcards": {"completed": 0, "correct": 0, "incorrect": 0},
+            "quiz": {"completed": 0, "correct": 0, "incorrect": 0},
+            "type": {"completed": 0, "correct": 0, "incorrect": 0},
+            "story": {"generated": 0},
+        },
+        "created_at": datetime.now().isoformat(),
+    }
+
+
+def _save_progress(unit_id: str, data: Dict[str, Any]):
+    _ensure_dir()
+    path = _progress_path(unit_id)
+    with open(path, "w", encoding="utf-8") as f:
+        json.dump(data, f, ensure_ascii=False, indent=2)
+
+
+class RewardPayload(BaseModel):
+    exercise_type: str  # flashcards, quiz, type, story
+    correct: bool = True
+    first_try: bool = True
+
+
+@router.get("/{unit_id}")
+def get_progress(unit_id: str):
+    """Get learning progress for a unit."""
+    return _load_progress(unit_id)
+
+
+@router.post("/{unit_id}/reward")
+def add_reward(unit_id: str, payload: RewardPayload):
+    """Record an exercise result and award coins."""
+    progress = _load_progress(unit_id)
+
+    # Update exercise stats
+    ex = progress["exercises"].get(payload.exercise_type, {"completed": 0, "correct": 0, "incorrect": 0})
+    ex["completed"] = ex.get("completed", 0) + 1
+    if payload.correct:
+        ex["correct"] = ex.get("correct", 0) + 1
+    else:
+        ex["incorrect"] = ex.get("incorrect", 0) + 1
+    progress["exercises"][payload.exercise_type] = ex
+
+    # Award coins
+    if payload.correct:
+        coins = 3 if payload.first_try else 1
+    else:
+        coins = 0
+    progress["coins"] = progress.get("coins", 0) + coins
+
+    # Update streak
+    today = date.today().isoformat()
+    last = progress.get("last_activity")
+    if last != today:
+        if last == (date.today().replace(day=date.today().day - 1)).isoformat() if date.today().day > 1 else None:
+            progress["streak_days"] = progress.get("streak_days", 0) + 1
+        elif last != today:
+            progress["streak_days"] = 1
+        progress["last_activity"] = today
+
+    # Award crowns for milestones
+    total_correct = sum(
+        e.get("correct", 0) for e in progress["exercises"].values() if isinstance(e, dict)
+    )
+    progress["crowns"] = total_correct // 20  # 1 crown per 20 correct answers
+
+    _save_progress(unit_id, progress)
+
+    return {
+        "coins_awarded": coins,
+        "total_coins": progress["coins"],
+        "crowns": progress["crowns"],
+        "streak_days": progress["streak_days"],
+    }
+
+
+@router.get("/")
+def list_all_progress():
+    """List progress for all units."""
+    _ensure_dir()
+    results = []
+    for f in Path(PROGRESS_DIR).glob("*.json"):
+        with open(f, "r", encoding="utf-8") as fh:
+            results.append(json.load(fh))
+    return results