refactor(git): rename refresh event to change, gate on actual diff

test/git/repo_test.lua

@@ -233,7 +233,7 @@ t.test("refresh emits change.paths listing structurally-changed paths", function
     t.write(dir, "a", "2")
     ---@type ow.Git.Repo.Change?
     local change_seen
-    local unsub = r:on("refresh", function(change)
+    local unsub = r:on("change", function(change)
         change_seen = change
     end)
     r:refresh()
@@ -263,7 +263,7 @@ t.test("submodule: eagerly creates child Repos and subscribes by default", funct
     t.write(outer_path .. "/sub", "a", "modified\n")
     ---@type ow.Git.Repo.Change?
     local outer_change
-    local unsub = outer:on("refresh", function(change)
+    local unsub = outer:on("change", function(change)
         outer_change = change
     end)
     inner:refresh()