feat: implement redaction UI and backend engine support for area-based PDF redactions

gateway/app/routers/edits.py

@@ -21,6 +21,19 @@ class TextOverlayData(BaseModel):
     fontFamily: str
     color: str
 
+class StampData(BaseModel):
+    text: str
+    x: float
+    y: float
+    width: float
+    height: float
+    textColor: str
+    backgroundColor: str
+    borderColor: str
+    fontSize: float = Field(..., gt=0)
+    includeDate: bool = False
+    timestamp: str | None = None
+
 
 class RedactionData(BaseModel):
     x: float
@@ -96,6 +109,12 @@ class TextOverlayOperation(BaseModel):
     pageIndex: int = Field(..., ge=0)
     data: TextOverlayData
 
+class StampOperation(BaseModel):
+    id: str
+    type: Literal["stamp"]
+    pageIndex: int = Field(..., ge=0)
+    data: StampData
+
 
 class RedactionOperation(BaseModel):
     id: str
@@ -299,6 +318,7 @@ class SignatureOperation(BaseModel):
 
 EditOperation = Annotated[
     TextOverlayOperation
+    | StampOperation
     | RedactionOperation
     | ImageOverlayOperation
     | HighlightOperation
@@ -329,8 +349,8 @@ class EditsRequest(BaseModel):
 _OP_PERMISSION = {
     "highlight": "canAnnotate", "underline": "canAnnotate", "strikeout": "canAnnotate",
     "squiggly": "canAnnotate", "comment": "canAnnotate", "freehand": "canAnnotate",
-    "free_text": "canAnnotate", "text_overlay": "canAnnotate", "image_overlay": "canAnnotate",
-    "delete_annotation": "canAnnotate", "update_annotation": "canAnnotate",
+    "free_text": "canAnnotate", "text_overlay": "canAnnotate", "stamp": "canAnnotate",
+    "image_overlay": "canAnnotate", "delete_annotation": "canAnnotate", "update_annotation": "canAnnotate",
     "replace_text": "canModify", "reflow_paragraph": "canModify", "redaction": "canModify",
     "update_field": "canFillForms",
     "page_rotation": "canAssemble", "page_deletion": "canAssemble", "page_reorder": "canAssemble",