feat: delete AI reports, Super Contexte versions, and KB entries

- database.py: add delete_ai_report(), delete_reasoning_state(), delete_kb_entry()
- reasoning.py: DELETE /api/reasoning/reports/{id}
- knowledge.py: DELETE /api/knowledge/history/{id} and /entries/{id}
- useApi.ts: useDeleteAiReport, useDeleteReasoningState, useDeleteKbEntry hooks
- RapportIA.tsx: trash icon on hover in archived reports sidebar
- SuperContexte.tsx: trash icon on hover for history versions and KB entries;
  both propagate onDelete through CategorySection down to KbEntry

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/routers/knowledge.py

@@ -8,6 +8,7 @@ from services.database import (
     get_kb_entries, get_all_kb_entries, save_kb_entry, update_kb_entry_status,
     get_latest_reasoning_state, get_reasoning_history, get_reasoning_state_by_id,
     save_reasoning_state, list_ai_reports, get_mtm_trades_with_traces, _trade_maturity,
+    delete_reasoning_state, delete_kb_entry,
 )
 
 router = APIRouter(prefix="/api/knowledge", tags=["knowledge"])
@@ -174,6 +175,24 @@ def get_state_version(state_id: int):
     return {"state": state}
 
 
+@router.delete("/history/{state_id}")
+def delete_state_version(state_id: int):
+    """Delete a reasoning state version by ID."""
+    deleted = delete_reasoning_state(state_id)
+    if not deleted:
+        raise HTTPException(404, "Version introuvable")
+    return {"deleted": True, "id": state_id}
+
+
+@router.delete("/entries/{entry_id}")
+def delete_entry(entry_id: int):
+    """Permanently delete a KB entry."""
+    deleted = delete_kb_entry(entry_id)
+    if not deleted:
+        raise HTTPException(404, "Entrée introuvable")
+    return {"deleted": True, "id": entry_id}
+
+
 @router.get("/entries")
 def list_entries(status: str = "all"):
     if status == "all":