feat(vwb): Améliorer outils IA et supprimer fallback statique

Backend:
- analyser_avec_ia.py: centraliser URL Ollama via os.environ.get()
- action_contracts.py: assouplir le contrat ai_analyze_text (mode texte
  sans ancre visuelle, accepter prompt ou analysis_prompt)
- intelligent_executor.py: supprimer le fallback coordonnées statiques
  quand la vision échoue — renvoyer not_found pour self-healing
- workflow.py: ajouter endpoints validate et export-training

run.sh:
- Corriger les ports (3000 → 3002) et le venv (venv_v3 → .venv)
- Lancer run_v4.sh au lieu de l'ancien run.sh

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

visual_workflow_builder/backend/api_v3/workflow.py

@@ -7,14 +7,18 @@ GET  /api/v3/workflow/{id}
 POST /api/v3/workflow/{id}/step
 PUT  /api/v3/workflow/{id}/step/{step_id}
 DELETE /api/v3/workflow/{id}/step/{step_id}
+POST /api/v3/workflow/{id}/validate
+POST /api/v3/workflow/{id}/export-training
 """
 
 from flask import jsonify, request
 from datetime import datetime
 import uuid
+import json
+import os
 from . import api_v3_bp
 from db.models import db, Workflow, Step, VisualAnchor, get_session_state
-from contracts.action_contracts import enforce_action_contract, ContractValidationError, get_required_params
+from contracts.action_contracts import enforce_action_contract, ContractValidationError, get_required_params, validate_action_contract
 
 
 def generate_id(prefix: str) -> str:
@@ -461,3 +465,166 @@ def reorder_steps(workflow_id: str):
             'success': False,
             'error': str(e)
         }), 500
+
+
+def _validate_workflow_steps(workflow):
+    """
+    Logique de validation partagée entre validate et export-training.
+    Retourne (errors, warnings, steps).
+    """
+    errors = []
+    warnings = []
+
+    steps = Step.query.filter_by(workflow_id=workflow.id).order_by(Step.order).all()
+
+    if len(steps) == 0:
+        errors.append("Le workflow n'a aucune étape")
+        return errors, warnings, steps
+
+    for i, step in enumerate(steps):
+        step_label = step.label or step.action_type
+        prefix = f"Étape {i+1} ({step_label})"
+
+        # Valider le contrat d'action
+        params = step.parameters or {}
+        violations = validate_action_contract(step.action_type, params)
+        for v in violations:
+            errors.append(f"{prefix}: {v.message}")
+
+        # Vérifier l'ancre visuelle si requise
+        required = get_required_params(step.action_type)
+        if 'visual_anchor' in required and not step.anchor_id:
+            errors.append(f"{prefix}: ancre visuelle manquante")
+
+        # Warnings
+        if not step.label or step.label == step.action_type:
+            warnings.append(f"{prefix}: pas de label personnalisé")
+
+    return errors, warnings, steps
+
+
+@api_v3_bp.route('/workflow/<workflow_id>/validate', methods=['POST'])
+def validate_workflow(workflow_id: str):
+    """
+    Valide la structure d'un workflow.
+
+    Response:
+    {
+        "success": true,
+        "is_valid": true/false,
+        "errors": [...],
+        "warnings": [...],
+        "step_count": 12
+    }
+    """
+    try:
+        workflow = Workflow.query.get(workflow_id)
+        if not workflow:
+            return jsonify({
+                'success': False,
+                'error': f"Workflow '{workflow_id}' non trouvé"
+            }), 404
+
+        errors, warnings, steps = _validate_workflow_steps(workflow)
+
+        is_valid = len(errors) == 0
+
+        print(f"{'✅' if is_valid else '❌'} [API v3] Validation workflow {workflow_id}: "
+              f"{len(errors)} erreur(s), {len(warnings)} warning(s)")
+
+        return jsonify({
+            'success': True,
+            'is_valid': is_valid,
+            'errors': errors,
+            'warnings': warnings,
+            'step_count': len(steps)
+        })
+
+    except Exception as e:
+        return jsonify({
+            'success': False,
+            'error': str(e)
+        }), 500
+
+
+@api_v3_bp.route('/workflow/<workflow_id>/export-training', methods=['POST'])
+def export_for_training(workflow_id: str):
+    """
+    Exporte un workflow validé au format JSON d'entraînement.
+
+    Response:
+    {
+        "success": true,
+        "export_path": "training_data/workflow_xxx_1234567890.json",
+        "training_entry": { ... }
+    }
+    """
+    try:
+        workflow = Workflow.query.get(workflow_id)
+        if not workflow:
+            return jsonify({
+                'success': False,
+                'error': f"Workflow '{workflow_id}' non trouvé"
+            }), 404
+
+        # Valider d'abord
+        errors, warnings, steps = _validate_workflow_steps(workflow)
+        if len(errors) > 0:
+            return jsonify({
+                'success': False,
+                'error': 'Le workflow contient des erreurs de validation',
+                'errors': errors
+            }), 400
+
+        # Construire le training entry
+        training_entry = {
+            'workflow_id': workflow.id,
+            'workflow_name': workflow.name,
+            'description': workflow.description or '',
+            'tags': workflow.tags if hasattr(workflow, 'tags') and workflow.tags else [],
+            'steps': [],
+            'exported_at': datetime.utcnow().isoformat(),
+            'metadata': {
+                'step_count': len(steps),
+                'action_types': list(set(s.action_type for s in steps)),
+                'has_anchors': any(s.anchor_id for s in steps),
+                'warnings': warnings
+            }
+        }
+
+        for step in steps:
+            step_data = {
+                'order': step.order,
+                'action_type': step.action_type,
+                'label': step.label,
+                'parameters': step.parameters or {},
+                'has_anchor': bool(step.anchor_id)
+            }
+            training_entry['steps'].append(step_data)
+
+        # Sauvegarder dans training_data/
+        training_dir = os.path.join(os.path.dirname(os.path.dirname(__file__)), 'training_data')
+        os.makedirs(training_dir, exist_ok=True)
+
+        timestamp = int(datetime.now().timestamp())
+        filename = f"workflow_{workflow_id}_{timestamp}.json"
+        filepath = os.path.join(training_dir, filename)
+
+        with open(filepath, 'w', encoding='utf-8') as f:
+            json.dump(training_entry, f, ensure_ascii=False, indent=2)
+
+        export_path = f"training_data/{filename}"
+
+        print(f"📦 [API v3] Workflow exporté pour entraînement: {export_path}")
+
+        return jsonify({
+            'success': True,
+            'export_path': export_path,
+            'training_entry': training_entry
+        })
+
+    except Exception as e:
+        return jsonify({
+            'success': False,
+            'error': str(e)
+        }), 500