feat(validator): R1 MVP P0 — OcrRoiChecker + orchestrator (flag OFF default)

Package core/validation/ minimal :
- result.py : Verdict, FailureCategory, ValidationResult
- pixel_diff_checker.py : wrapper de ReplayVerifier.verify_action
- ocr_roi_checker.py : ROI 80px autour du clic, détecte WRONG_APPLICATION
  via SUSPECT_TOKENS (edge/https/explorateur de fichiers/…)
- orchestrator.py : Validator dispatch action_type → checkers + agrégation

Wiring api_stream.py:3646 derrière RPA_VALIDATOR_V2_ENABLED (OFF par défaut).
Si verdict ≠ COMPLETE, override report.success=False et expose failure_category
dans result_entry. Zero régression flag OFF.

Tests :
- tests/unit/test_validator_v2.py : 13 tests (Checkers + Validator + sérialisation)
- tests/integration/test_validator_step10.py : 2 tests reproduisant le bug
  replay_sess_4c38dbb8 / act_raw_6c1432b3 (clic Enregistrer fait basculer
  vers Explorateur de fichiers) — Validator retourne WRONG_APPLICATION

Activation pour test live : RPA_VALIDATOR_V2_ENABLED=true

Cf. docs/recherche/SPEC_VALIDATOR_MATRICE.md, AXE_B2_DEEP_VALIDATOR.md.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

core/validation/result.py

@@ -0,0 +1,53 @@
+"""Dataclasses du Validator — Verdict, FailureCategory, ValidationResult.
+
+Cf. SPEC_VALIDATOR_MATRICE.md §1 et AXE_B2_DEEP_VALIDATOR.md §3.1.
+"""
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+from enum import Enum
+from typing import Any, Dict, Optional
+
+
+class Verdict(str, Enum):
+    """Trois verdicts possibles (calque Skyvern complete/terminate/continue)."""
+    COMPLETE = "complete"      # l'action a eu l'effet voulu
+    CONTINUE = "continue"      # effet pas encore visible → recheck/wait
+    TERMINATE = "terminate"    # échec irrécupérable → pause supervisée
+
+
+class FailureCategory(str, Enum):
+    """Classification des échecs (restreinte au contexte rpa_vision_v3)."""
+    WRONG_TARGET = "wrong_target"
+    WRONG_APPLICATION = "wrong_application"  # bug step 10 (clic hors-app)
+    NO_VISUAL_CHANGE = "no_visual_change"
+    UNEXPECTED_DIALOG = "unexpected_dialog"
+    OCR_TEXT_MISSING = "ocr_text_missing"
+    SCHEMA_INVALID = "schema_invalid"
+    UI_LOADING = "ui_loading"
+    UNKNOWN = "unknown"
+
+
+@dataclass
+class ValidationResult:
+    """Résultat d'un check. Toujours sérialisable JSON."""
+    verdict: Verdict
+    confidence: float
+    check_used: str
+    elapsed_ms: float
+    reasoning: str = ""
+    failure_category: Optional[FailureCategory] = None
+    raw_evidence: Dict[str, Any] = field(default_factory=dict)
+
+    def to_dict(self) -> Dict[str, Any]:
+        return {
+            "verdict": self.verdict.value,
+            "confidence": round(self.confidence, 3),
+            "check_used": self.check_used,
+            "elapsed_ms": round(self.elapsed_ms, 1),
+            "reasoning": self.reasoning,
+            "failure_category": (
+                self.failure_category.value if self.failure_category else None
+            ),
+            "raw_evidence": self.raw_evidence,
+        }