fix: draggable pin writeback and click-to-place event collision

Three related bugs in the maplibre reactive signal plumbing:

1. Draggable marker coordinates never updated because dragendHandlerJS
   queries for hidden inputs matching LngSignal/LatSignal IDs, but
   Element() never rendered those inputs. Add them after the marker
   data-effect divs.

2. Click-to-place marker didn't appear until moveend because Element()
   rendered a bare hidden input for each event signal, colliding with
   the user's action-bearing input (same data-bind, querySelector finds
   the bare one first). Remove the internal event inputs — the user
   provides their own via MapEvent.Input().

3. The moveend handler dispatched 'input' on ALL data-bind inputs in
   the wrapper, accidentally triggering event inputs. Add an else-return
   so only the 5 viewport signal inputs get dispatched.

maplibre/js.go

@@ -140,6 +140,7 @@ func initScript(m *Map) string {
 		`else if(sig===%[4]s)inp.value=map.getZoom();`+
 		`else if(sig===%[5]s)inp.value=map.getBearing();`+
 		`else if(sig===%[6]s)inp.value=map.getPitch();`+
+		`else return;`+
 		`inp.dispatchEvent(new Event('input',{bubbles:true}));`+
 		`});`+
 		`});`,

maplibre/maplibre.go

@@ -122,11 +122,14 @@ func (m *Map) Element(extra ...h.H) h.H {
 		}
 	}
 
-	// Event listener binding elements
-	for _, ev := range m.events {
-		children = append(children,
-			h.Input(h.Type("hidden"), ev.signal.Bind()),
-		)
+	// Hidden inputs for signal-backed marker position writeback (drag → signal)
+	for _, me := range m.markers {
+		if me.marker.LngSignal != nil && me.marker.LatSignal != nil {
+			children = append(children,
+				h.Input(h.Type("hidden"), me.marker.LngSignal.Bind()),
+				h.Input(h.Type("hidden"), me.marker.LatSignal.Bind()),
+			)
+		}
 	}
 
 	children = append(children, extra...)