fix: Improve AI price digit recognition to avoid 1.99/9.99 confusion

**Problem:**
AI was misreading prices: "1,99 €" detected as "9,99 €" with 90% confidence.
This is a critical OCR error where similar-looking digits (1, 7, 8, 9) are confused.
The model google/gemini-2.5-flash-lite made basic digit recognition mistakes.

**Root Cause:**
- AI vision models can confuse visually similar digits
- No specific instructions in prompt to verify digit accuracy
- No validation that detected price matches text context
- Model may be too lightweight for reliable OCR

**Solution: Three-Part Fix**

1. **Enhanced Prompt with Digit Verification** (ai_schema.py:145-149)
   - Added "CRITICAL - Read digits carefully" section
   - Explicit warning: "1,99 €" is NOT "9,99 €"
   - Instructions to double-check digits 1, 7, 8, 9 (visually similar)
   - Context check: Small prices (< 5€) are common
   - Verify price makes sense for product type

2. **More Examples in Prompt** (ai_schema.py:152-153)
   - Added: "1,99 €" -> 1.99 (NOT 9.99)
   - Added: "0,99 €" -> 0.99 (NOT 9.99)
   - Reinforces correct parsing of small prices

3. **Price Extraction Logging** (ai_service.py:349-355)
   - Extract ALL prices from text with regex: \d+[,\.]\d{2}\s*€
   - Log first 10 prices found: ["1,99 €", "2,99 €", ...]
   - Allows debugging: Is correct price in text?
   - Logs warning if NO prices found in text

4. **Debug Logs to INFO** (ai_service.py:347, 361)
   - Changed logger.debug → logger.info for text/prompt preview
   - Now visible in production logs for diagnosis

**Expected Improvement:**
- AI should now pay closer attention to digit shapes
- Lower confidence (0.5-0.7) if digits are unclear
- Better accuracy for small prices (0,99 - 4,99)
- Logs will show if problem is in text extraction or AI vision

**Testing:**
After restart, logs will show:
```
INFO - Cleaned text preview: 'Lutin de Noël 1,99 € Ajouter...'
INFO - Prices found in text: ['1,99 €', '2,99 €']
INFO - AI Response: {"price": 1.99, "price_confidence": 0.85}
```

If AI still returns wrong price but text has correct price,
then model is insufficient and should be upgraded to:
- google/gemini-2.0-flash-exp
- anthropic/claude-3-haiku
- openai/gpt-4o-mini

app/ai_schema.py

@@ -141,11 +141,21 @@ EXTRACTION_PROMPT_TEMPLATE = """Extract product price and stock status from this
 - Extract as DECIMAL NUMBER (convert comma to dot): 12,99 -> 12.99
 - Ignore crossed-out/barré prices (old prices)
 - If multiple prices, take the current/main price (not the original)
+
+**CRITICAL - Read digits carefully:**
+- PAY CLOSE ATTENTION to first digit: "1,99 €" is NOT "9,99 €"
+- Double-check: Is it 1, 7, 8, or 9? These look similar
+- Small prices (< 5€) are common: 0,99 €, 1,49 €, 1,99 €, 2,99 €, 3,99 €, 4,99 €
+- VERIFY the price makes sense for the product type
+
 - Examples of valid prices:
+  * "1,99 €" -> 1.99 (NOT 9.99)
+  * "0,99 €" -> 0.99 (NOT 9.99)
   * "89,99 €" -> 89.99
   * "1 234,56 €" -> 1234.56
   * "PRIX DÉTECTÉ: 89,99 €" -> 89.99
 - If you find ANY price with € symbol, extract it with confidence >= 0.8
+- If digits are unclear or blurry, reduce confidence to 0.5-0.7
 - If unclear: set null and confidence < 0.5
 
 **STOCK:**

app/services/ai_service.py

@@ -343,14 +343,22 @@ class AIService:
                 if len(cleaned_text) > MAX_TEXT_LENGTH:
                     cleaned_text = cleaned_text[:MAX_TEXT_LENGTH] + "...(truncated)"
                 logger.info(f"Added text context (original: {len(page_text)}, cleaned: {len(cleaned_text)})")
-                # Debug: Log first 500 chars of cleaned text to see what AI receives
-                logger.debug(f"Cleaned text preview: {cleaned_text[:500]!r}")
+                # Log first 500 chars of cleaned text to see what AI receives
+                logger.info(f"Cleaned text preview: {cleaned_text[:500]!r}")
+
+                # Extract all potential prices from text for debugging
+                import re
+                price_patterns = re.findall(r'\d+[,\.]\d{2}\s*€', cleaned_text)
+                if price_patterns:
+                    logger.info(f"Prices found in text: {price_patterns[:10]}")  # First 10 prices
+                else:
+                    logger.warning("No prices found in text with € symbol")
             else:
                 logger.warning("No page_text provided - AI will only use screenshot")
 
             prompt = get_extraction_prompt(cleaned_text if cleaned_text else None)
-            # Debug: Log prompt preview
-            logger.debug(f"Prompt preview (first 300 chars): {prompt[:300]!r}")
+            # Log prompt preview
+            logger.info(f"Prompt preview (first 300 chars): {prompt[:300]!r}")
 
             # Call LLM
             response_text = await cls.call_llm(prompt, data_url, config)