add: CACHE_BREAKER env var

crates/app/src/assets.rs

@@ -495,6 +495,13 @@ pub(crate) async fn initial_context(
     }
 
     ctx.insert("lang", &lang.data);
-    ctx.insert("random_cache_breaker", &CACHE_BREAKER.clone());
+    ctx.insert(
+        "random_cache_breaker",
+        &if let Ok(c) = std::env::var("CACHE_BREAKER") {
+            c
+        } else {
+            CACHE_BREAKER.clone()
+        },
+    );
     ctx
 }