Add Java orchestrator to connect to the AI engine (#6003)

# Description of Changes
Add Java orchestration layer which can connect and go back and forth
with the AI engine to get results for the user. It's expected that the
AI engine will not be publicly available and this Java layer will always
be in front of it, to manage sessions and auth etc.

engine/src/stirling/contracts/pdf_edit.py

@@ -6,30 +6,29 @@ from pydantic import Field
 
 from stirling.models import ApiModel
 
-from .common import ToolOperationStep
+from .common import ToolOperationStep, WorkflowOutcome
 
 
 class PdfEditRequest(ApiModel):
     user_message: str
-    conversation_id: str | None = None
     file_names: list[str] = Field(default_factory=list)
 
 
 class EditPlanResponse(ApiModel):
-    outcome: Literal["plan"] = "plan"
+    outcome: Literal[WorkflowOutcome.PLAN] = WorkflowOutcome.PLAN
     summary: str
     rationale: str | None = None
     steps: list[ToolOperationStep]
 
 
 class EditClarificationRequest(ApiModel):
-    outcome: Literal["need_clarification"] = "need_clarification"
+    outcome: Literal[WorkflowOutcome.NEED_CLARIFICATION] = WorkflowOutcome.NEED_CLARIFICATION
     question: str
     reason: str
 
 
 class EditCannotDoResponse(ApiModel):
-    outcome: Literal["cannot_do"] = "cannot_do"
+    outcome: Literal[WorkflowOutcome.CANNOT_DO] = WorkflowOutcome.CANNOT_DO
     reason: str