Fix modal flash when clicking actions (vote, like, etc.)

- Skip marker refresh when post modal is open (update UI in-place)
- Add stopPropagation to vote buttons to prevent event bubbling

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/Map/markerManager.js

@@ -1964,8 +1964,8 @@ export function openCenteredOverlay({ map, post, theme, fullScreen = false }) {
     };
     const voteUp = rail.querySelector(".sw-truth-rail-btn-up");
     const voteDown = rail.querySelector(".sw-truth-rail-btn-down");
-    if (voteUp) voteUp.addEventListener("click", () => doVote("true"));
-    if (voteDown) voteDown.addEventListener("click", () => doVote("false"));
+    if (voteUp) voteUp.addEventListener("click", (e) => { e.stopPropagation(); doVote("true"); });
+    if (voteDown) voteDown.addEventListener("click", (e) => { e.stopPropagation(); doVote("false"); });
   }
 
   applyAuthUI();

src/components/Map/usePostsEngine.js

@@ -1427,8 +1427,14 @@ export function usePostsEngine({
         }
         if (changed) {
           allPostsRef.current = updated;
+          // Skip full marker refresh if this post's modal is open - we update UI in-place below
+          const map = mapRef.current;
+          const ov = map?.__swCenteredOverlay;
+          const isModalOpen = ov && ov.postId === postId;
+          if (!isModalOpen) {
             refreshVisibleAndMarkers(timeHours, true);
           }
+        }
       };
 
       const needsResolve = (value) =>