feat(027): Final Phase T038-T043 implementation

- T038: SessionEvent logger and persistence logic
  - Added SessionEventLogger service with explicit audit event persistence
  - Added SessionEvent model with events relationship on DatasetReviewSession
  - Integrated event logging into orchestrator flows and API mutation endpoints

- T039: Semantic source version propagation
  - Added source_version column to SemanticFieldEntry
  - Added propagate_source_version_update() to SemanticResolver
  - Preserves locked/manual field invariants during propagation

- T040: Batch approval API and UI actions
  - Added batch semantic approval endpoint (/fields/semantic/approve-batch)
  - Added batch mapping approval endpoint (/mappings/approve-batch)
  - Added batch approval actions to SemanticLayerReview and ExecutionMappingReview components
  - Aligned batch semantics with single-item approval contracts

- T041: Superset compatibility matrix tests
  - Added test_superset_matrix.py with preview and SQL Lab fallback coverage
  - Tests verify client method preference and matrix fallback behavior

- T042: RBAC audit sweep on session-mutation endpoints
  - Added _require_owner_mutation_scope() helper
  - Applied owner guards to update_session, delete_session, and all mutation endpoints
  - Ensured no bypass of existing permission checks

- T043: i18n coverage for dataset-review UI
  - Added workspace state labels (empty/importing/review) to en.json and ru.json
  - Added batch action labels for semantics and mappings
  - Fixed workspace state comparison to lowercase strings
  - Removed hardcoded workspace state display strings

Signed-off-by: Implementation Specialist <impl@ss-tools>

backend/src/models/dataset_review.py

@@ -132,6 +132,7 @@ class DatasetReviewSession(Base):
     previews = relationship("CompiledPreview", back_populates="session", cascade="all, delete-orphan")
     run_contexts = relationship("DatasetRunContext", back_populates="session", cascade="all, delete-orphan")
     export_artifacts = relationship("ExportArtifact", back_populates="session", cascade="all, delete-orphan")
+    events = relationship("SessionEvent", back_populates="session", cascade="all, delete-orphan")
 # [/DEF:DatasetReviewSession:Class]
 
 # [DEF:BusinessSummarySource:Class]
@@ -303,6 +304,7 @@ class SemanticFieldEntry(Base):
     display_format = Column(String, nullable=True)
     provenance = Column(SQLEnum(FieldProvenance), nullable=False, default=FieldProvenance.UNRESOLVED)
     source_id = Column(String, nullable=True)
+    source_version = Column(String, nullable=True)
     confidence_rank = Column(Integer, nullable=True)
     is_locked = Column(Boolean, nullable=False, default=False)
     has_conflict = Column(Boolean, nullable=False, default=False)
@@ -567,6 +569,7 @@ class ClarificationAnswer(Base):
     answer_value = Column(Text, nullable=True)
     answered_by_user_id = Column(String, nullable=False)
     impact_summary = Column(Text, nullable=True)
+    user_feedback = Column(String, nullable=True) # up, down, null
     created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
 
     question = relationship("ClarificationQuestion", back_populates="answer")
@@ -627,6 +630,24 @@ class DatasetRunContext(Base):
     session = relationship("DatasetReviewSession", back_populates="run_contexts")
 # [/DEF:DatasetRunContext:Class]
 
+# [DEF:SessionEvent:Class]
+class SessionEvent(Base):
+    __tablename__ = "session_events"
+
+    session_event_id = Column(String, primary_key=True, default=lambda: str(uuid.uuid4()))
+    session_id = Column(String, ForeignKey("dataset_review_sessions.session_id"), nullable=False)
+    actor_user_id = Column(String, ForeignKey("users.id"), nullable=False)
+    event_type = Column(String, nullable=False)
+    event_summary = Column(Text, nullable=False)
+    current_phase = Column(String, nullable=True)
+    readiness_state = Column(String, nullable=True)
+    event_details = Column(JSON, nullable=False, default=dict)
+    created_at = Column(DateTime, default=datetime.utcnow, nullable=False)
+
+    session = relationship("DatasetReviewSession", back_populates="events")
+    actor = relationship("User")
+# [/DEF:SessionEvent:Class]
+
 # [DEF:ArtifactType:Class]
 class ArtifactType(str, enum.Enum):
     DOCUMENTATION = "documentation"