fix: Improve Fnac image extraction and add Shopify fallbacks

Fixes two issues:

**1. Fnac - No Images Displayed**
Problem: FnacParser only searched for images in parent container,
missing images nested directly in the link element.

Solution: Two-priority search
- PRIORITY 1: Search in link element first (picture, img)
- PRIORITY 2: Search in parent container
- Added warning log when no image found
- Ensures parent is always defined before use

**2. L'Incroyable - 0 Products (Shopify sites)**
Problem: GenericParser fallbacks didn't include Shopify patterns.
L'Incroyable uses Shopify structure with /products/ URLs.

Solution: Added Shopify-specific fallbacks
- a[href*='/products/'] (Shopify product URLs)
- a.product-card__link (Shopify class)
- a[href*='/collections/'] (Shopify collections)
- li[class*='product'] a (list-based layouts)

**Fallback Order (now 17 selectors):**
1. Product URL patterns (Shopify, generic)
2. Semantic classes (article, .product-card)
3. Shopify-specific selectors
4. Generic structure patterns
5. Last resort wildcards

**Expected Impact:**
- ✅ Fnac images should now display
- ✅ L'Incroyable should find products (Shopify)
- ✅ Better coverage of Shopify-based stores

app/services/parsers/generic_parser.py

@@ -73,6 +73,7 @@ class GenericParser(BaseParser):
             fallback_selectors = [
                 # Product-specific URLs
                 "a[href*='/produit']",
+                "a[href*='/products/']",  # Shopify
                 "a[href*='/product']",
                 "a[href*='/p/']",
                 "a[href*='/item']",
@@ -82,9 +83,13 @@ class GenericParser(BaseParser):
                 ".product-card a[href]",
                 ".product-item a[href]",
                 "[class*='product'] a[href]",
+                # Shopify specific
+                "a.product-card__link",
+                "a[href*='/collections/']",
                 # Generic structure
                 "article[class*='product'] a",
                 "div[class*='product'] a",
+                "li[class*='product'] a",
                 # Very generic (last resort)
                 "a[class*='product']",
             ]