feat(investigations): add event impact and work-order feedback flows

Add isolated burst and pollution impact evidence, parallel work-order workflows, persisted notifications and graph updates.

Checkpoint current code. Known follow-ups remain for large pollution result previews and graceful geometry failure.

app/domain/schemas/operational_task.py

@@ -252,6 +252,10 @@ class InvestigationDiagramNodeRef(_InvestigationDiagramNode):
 
 
 class InvestigationGraphNodeUpdate(_InvestigationDiagramNode):
+    label: NonEmptyStr | None = Field(default=None, description=(
+        "Required for a new node. Omit or use null to retain an existing node's label. "
+        "Use the same node_id to revise status or detail without adding another step."
+    ))
     status: InvestigationNodeAnnotation | None = Field(default=None, description=(
         "Optional reference annotation: reference, recorded finding, needs_input, failed attempt, or not_taken. "
         "No live node/task binding or per-step synchronization is required."
@@ -752,7 +756,7 @@ class ScadaChartGap(StrictModel):
 
 class ScadaChartContext(StrictModel):
     role: Literal["current", "comparison"]
-    metric: Literal["pressure", "flow"]
+    metric: Literal["pressure", "flow", "quality"]
     unit: Annotated[str, Field(min_length=1, max_length=128)]
     window_start: WorkbenchDateTime
     window_end: WorkbenchDateTime
@@ -1015,6 +1019,13 @@ class HumanEvidenceCommand(StrictModel):
     evidence: EvidenceInput
 
 
+class WorkOrderNotificationReference(StrictModel):
+    source_event_id: NonEmptyStr
+    source_revision: PositiveInt
+    evidence_id: NonEmptyStr | None = None
+    status: Literal["scheduled", "assigned", "in_progress", "awaiting_feedback", "completed", "cancelled", "failed"]
+
+
 class OperationalTaskNotification(StrictModel):
     notification_id: UUID
     task_id: UUID
@@ -1022,7 +1033,7 @@ class OperationalTaskNotification(StrictModel):
         "task_created", "action_pending", "report_updated", "task_completed",
         "task_failed", "run_delivery_degraded", "access_approval_pending",
         "action_approval_pending", "human_input_required",
-        "external_coordination_failed"
+        "external_coordination_failed", "work_order_feedback"
     ]
     title: NonEmptyStr
     description: NonEmptyStr
@@ -1031,6 +1042,8 @@ class OperationalTaskNotification(StrictModel):
     subject_type: Literal["task", "run", "access_request", "action", "question"] = "task"
     subject_id: UUID | None = None
     report_reference: InvestigationReportReference | None = None
+    work_order_action: HumanApprovalAction | None = None
+    work_order_reference: WorkOrderNotificationReference | None = None
     resolved_at: WorkbenchDateTime | None = None
     resolution_reason: NonEmptyStr | None = None
     status: Literal["unread", "read"]