feat: stabilize category rule operations

approve dcy-001 and add REQ/BAT evidence

pass selected DB path through Streamlit rule actions

expose delete_category_rule MCP tool

add category rule deletion regression

dashboard/app.py

@@ -825,12 +825,12 @@ def page_rules(db_path: str) -> None:
 
     c1, c2, c3 = st.columns(3)
     if c1.button("기본 규칙 seed/update"):
-        res = service.seed_default_category_rules()
+        res = service.seed_default_category_rules(db_path=db_path)
         clear_cache(); st.success(res)
     if c2.button("규칙 preview"):
-        st.session_state["rule_preview"] = service.preview_categorization(limit=5000)
+        st.session_state["rule_preview"] = service.preview_categorization(limit=5000, db_path=db_path)
     if c3.button("규칙 적용"):
-        res = service.apply_categorization_rules(limit=5000)
+        res = service.apply_categorization_rules(limit=5000, db_path=db_path)
         clear_cache(); st.success(f"{res.get('applied_count', 0)}건 적용")
     if "rule_preview" in st.session_state:
         prev = st.session_state["rule_preview"]