scraper: add engine stats API for dashboard

- EngineTracker.get_stats() returns detailed per-engine metrics
- get_scraper_stats() module function for external access
- includes success counts, backoff status, availability

scraper.py

@@ -104,6 +104,43 @@ class EngineTracker(object):
         in_backoff = len(self.engines) - available
         return available, in_backoff, len(self.engines)
 
+    def get_stats(self):
+        """Return detailed stats for API/dashboard."""
+        now = time.time()
+        available = self.get_available()
+        available_ids = set(ident for _, ident in available)
+
+        engines_list = []
+        for eng, ident in self.engines:
+            # Shorten identifier for display
+            if '/' in ident:
+                name = ident.split('/')[2]  # extract domain from URL
+            else:
+                name = ident
+
+            backoff_remaining = 0
+            if ident in self.backoff_until:
+                backoff_remaining = max(0, int(self.backoff_until[ident] - now))
+
+            engines_list.append({
+                'name': name,
+                'available': ident in available_ids,
+                'successes': self.success_count.get(ident, 0),
+                'failures': self.failures.get(ident, 0),
+                'backoff_remaining': backoff_remaining
+            })
+
+        # Sort by success count descending
+        engines_list.sort(key=lambda x: -x['successes'])
+
+        return {
+            'available': len(available),
+            'in_backoff': len(self.engines) - len(available),
+            'total': len(self.engines),
+            'total_successes': sum(self.success_count.values()),
+            'engines': engines_list[:20]  # Top 20 engines
+        }
+
     def load_state(self):
         """Load persisted backoff state from JSON file."""
         if not os.path.exists(self.state_file):
@@ -174,6 +211,13 @@ class EngineTracker(object):
 engine_tracker = None
 
 
+def get_scraper_stats():
+    """Get scraper stats for API/dashboard."""
+    if engine_tracker is None:
+        return None
+    return engine_tracker.get_stats()
+
+
 def build_search_query(sqlite=None):
     """Build a search query using configured sources."""
     search = ''