feat(governance): expose km draft dedupe plan

apps/api/src/models/governance.py

@@ -118,6 +118,34 @@ class GovernanceQueueResponse(BaseModel):
     )
 
 
+# =============================================================================
+# Endpoint 2B: KM review draft dedupe
+# =============================================================================
+
+class KnowledgeReviewDraftDedupeGroup(BaseModel):
+    governance_event_id: str
+    canonical_entry_id: str
+    canonical_title: str
+    canonical_updated_at: datetime | None = None
+    preferred_source: Literal["dispatch_context", "latest_review_draft"]
+    duplicate_entry_ids: list[str] = Field(default_factory=list)
+    duplicate_count: int
+    total_entries: int
+    suggested_action: str
+    owner_action: str
+    writes_on_read: bool = False
+    can_archive_without_owner_approval: bool = False
+
+
+class KnowledgeReviewDraftDedupeResponse(BaseModel):
+    schema_version: str = "km_review_draft_dedupe_v1"
+    total_review_drafts: int
+    event_group_total: int
+    duplicate_draft_total: int
+    groups: list[KnowledgeReviewDraftDedupeGroup]
+    generated_at: datetime
+
+
 # =============================================================================
 # Endpoint 3: summary
 # =============================================================================