refactor(backend): update Pydantic models for ingestion and query

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/app/models/common.py

@@ -0,0 +1,8 @@
+from pydantic import BaseModel
+
+
+class SourceMetadata(BaseModel):
+    filename: str
+    upload_date: str
+    content_summary: str
+    chunk_index: int

backend/app/models/ingest.py

@@ -1,27 +1,7 @@
-from datetime import datetime
-from typing import List
-
 from pydantic import BaseModel
 
 
-class SourceMetadata(BaseModel):
-    filename: str
-    upload_date: str
-    content_summary: str
-    chunk_index: int
-
-
 class IngestResponse(BaseModel):
     document_id: str
     chunk_count: int
     filename: str
-
-
-class QueryRequest(BaseModel):
-    question: str
-
-
-class QueryResponse(BaseModel):
-    keywords: List[str]
-    answer: str
-    sources: List[SourceMetadata]

backend/app/models/query.py

@@ -0,0 +1,15 @@
+from typing import List
+
+from pydantic import BaseModel
+
+from app.models.common import SourceMetadata
+
+
+class QueryRequest(BaseModel):
+    question: str
+
+
+class QueryResponse(BaseModel):
+    keywords: List[str]
+    answer: str
+    sources: List[SourceMetadata]