feat: persist package amount metadata in backend (#356)

* feat: add package amount persistence and backend route support

* test: align backend test schemas with medication metadata fields

* fix(backend): restore intake usage normalizer for planner endpoint

* fix(backend): keep export typing compatible before liquid-unit stack step

backend/drizzle/meta/_journal.json

@@ -78,6 +78,13 @@
       "when": 1771694832866,
       "tag": "0010_mean_spot",
       "breakpoints": true
+    },
+    {
+      "idx": 11,
+      "version": "6",
+      "when": 1772219947541,
+      "tag": "0011_stiff_randall_flagg",
+      "breakpoints": true
     }
   ]
 }