feat: Rebuild search system with modular, site-specific parsers

Complete refactoring of the search module for robustness and reliability:

**New Architecture:**
- Modular parser system with specialized parsers for each major site
- Factory pattern for automatic parser selection
- Generic fallback parser for sites without specific implementation

**Specialized Parsers:**
- ✅ Amazon.fr - Robust parser with multiple fallback selectors
  - Handles sponsored products, Prime eligibility, ratings, reviews
  - Based on proven amazon_scraper_v2.py implementation
- ✅ Cdiscount.com - Optimized for Cdiscount's HTML structure
- ✅ Fnac.com - Handles Fnac's picture elements and article structure
- ✅ Darty.com - Specialized for electronics retailer
- ✅ Boulanger.com - Optimized for Boulanger's product cards

**Key Features:**
- Multiple fallback selectors for each element (title, price, image)
- Proper price parsing for French format (1 234,56 €)
- Rating and review count extraction
- Stock status detection
- Image URL extraction with multiple attribute fallbacks
- Query filtering to ensure relevant results

**Benefits:**
- Much more robust than previous generic parsing
- Easier to maintain (one parser per site)
- Easily extensible (add new parser for new site)
- Better error handling and logging
- Higher success rate for product extraction

**Updated Services:**
- improved_search_service.py now uses ParserFactory
- Legacy _parse_results marked as deprecated
- Conversion layer between ProductResult and SearchResult

This implements the Amazon France model across all major sites
for consistent, reliable product search results.

app/services/parsers/__init__.py

@@ -0,0 +1,25 @@
+"""
+Site-Specific Parsers for Robust Product Search
+Each parser implements specialized logic for extracting search results and product details
+"""
+
+from .base_parser import BaseParser, ProductResult
+from .parser_factory import ParserFactory
+from .amazon_parser import AmazonParser
+from .cdiscount_parser import CdiscountParser
+from .fnac_parser import FnacParser
+from .darty_parser import DartyParser
+from .boulanger_parser import BoulangerParser
+from .generic_parser import GenericParser
+
+__all__ = [
+    "BaseParser",
+    "ProductResult",
+    "ParserFactory",
+    "AmazonParser",
+    "CdiscountParser",
+    "FnacParser",
+    "DartyParser",
+    "BoulangerParser",
+    "GenericParser",
+]