refactor: nettoyage agent + fix SomEngine review (singleton partagé, cache, thread-safe)

Nettoyage Windows agent :
- Suppression lea_ui inutilisés (chat_widget, overlay, styles, etc. — -1991 lignes)
- Suppression window_info*.py dupliqués (racine + core/ — -494 lignes)
- build/ + dist/ supprimés (48 MB PyInstaller abandonné, gitignorés)

Fix SomEngine (review quality guardian) :
- Singleton GPU partagé via get_shared_engine() (1 instance au lieu de 2)
- Thread-safe avec threading.Lock (double-checked locking)
- Cache SomResult par screenshot_id (max 50, évite YOLO+OCR redondants)
- Fuite fichier temp docTR corrigée (finally block)
- Chemin YOLO configurable via SOM_YOLO_WEIGHTS env var
- Guard som_image None avant VLM
- Match texte partiel : len(label) >= 3

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

agent_v0/server_v1/stream_processor.py

@@ -431,21 +431,17 @@ def _needs_post_wait(action: dict) -> int:
 # SomEngine — enrichissement Set-of-Mark des clics pendant le build_replay
 # ---------------------------------------------------------------------------
 
-_som_engine = None  # Singleton, chargé à la demande
+_som_cache: Dict[str, Any] = {}  # screenshot_id -> SomResult (cache build_replay)
+_SOM_CACHE_MAX = 50
 
 
 def _get_som_engine():
-    """Singleton SomEngine (lazy-loaded, GPU)."""
-    global _som_engine
-    if _som_engine is None:
-        try:
-            from core.detection.som_engine import SomEngine
-            _som_engine = SomEngine(device="cuda")
-            logger.info("SomEngine initialisé (lazy singleton)")
-        except Exception as e:
-            logger.warning("SomEngine non disponible : %s", e)
-            _som_engine = False  # Marqueur "indisponible"
-    return _som_engine if _som_engine is not False else None
+    """Singleton SomEngine partagé."""
+    try:
+        from core.detection.som_engine import get_shared_engine
+        return get_shared_engine()
+    except ImportError:
+        return None
 
 
 def _som_identify_clicked_element(
@@ -486,19 +482,38 @@ def _som_identify_clicked_element(
         if not full_path.is_file():
             return None
 
-    try:
-        from PIL import Image
-        img = Image.open(full_path).convert("RGB")
-    except Exception as e:
-        logger.debug("SoM: impossible de charger %s : %s", full_path, e)
-        return None
+    # Vérifier le cache SomResult par (session_dir, screenshot_id)
+    cache_key = f"{session_dir}:{screenshot_id}"
+    if cache_key in _som_cache:
+        result = _som_cache[cache_key]
+    else:
+        try:
+            from PIL import Image
+            img = Image.open(full_path).convert("RGB")
+        except Exception as e:
+            logger.debug("SoM: impossible de charger %s : %s", full_path, e)
+            return None
 
-    # Lancer SomEngine
-    try:
-        result = engine.analyze(img)
-    except Exception as e:
-        logger.warning("SoM: erreur d'analyse : %s", e)
-        return None
+        # Lancer SomEngine
+        try:
+            result = engine.analyze(img)
+        except Exception as e:
+            logger.warning("SoM: erreur d'analyse : %s", e)
+            return None
+
+        # Stocker dans le cache (éléments seulement, pas l'image annotée)
+        from core.detection.som_engine import SomResult
+        cached = SomResult(
+            elements=result.elements,
+            width=result.width,
+            height=result.height,
+            analysis_time_ms=result.analysis_time_ms,
+        )
+        if len(_som_cache) >= _SOM_CACHE_MAX:
+            # Supprimer la plus ancienne entrée (FIFO)
+            oldest_key = next(iter(_som_cache))
+            del _som_cache[oldest_key]
+        _som_cache[cache_key] = cached
 
     if not result.elements:
         return None