fix: distinguish partial vessel snapshots from stale data

src/data/feedState.js

@@ -3,7 +3,7 @@ import { GUIDANCE_STATUSES } from '../loadingFeedback.js';
 /**
  * Normalize heterogeneous layer stats into one honest control-chip state.
  * @param {object|null} stats Layer getStats() result.
- * @returns {'nominal'|'loading'|'degraded'|'stale'|'fallback'|'unavailable'} Feed state.
+ * @returns {'nominal'|'loading'|'degraded'|'stale'|'partial'|'fallback'|'unavailable'} Feed state.
  */
 export function layerFeedState(stats = {}) {
   const state = stats || {};
@@ -50,5 +50,6 @@ export function layerFeedState(stats = {}) {
     state.available === false
   )
     return 'degraded';
+  if (state.partial === true) return 'partial';
   return 'nominal';
 }