refactor(git): consolidate empty_buf with optional name + bufhidden

lua/git/show.lua

@@ -77,19 +77,6 @@ local function is_zero(sha)
     return sha == nil or sha:match("^0+$") ~= nil
 end
 
----@param ref string  buffer-name ref segment
----@param path string
----@return integer
-local function empty_buf(ref, path)
-    local buf = vim.api.nvim_create_buf(false, true)
-    vim.bo[buf].buftype = "nofile"
-    vim.bo[buf].bufhidden = "hide"
-    vim.bo[buf].swapfile = false
-    vim.bo[buf].modifiable = false
-    pcall(vim.api.nvim_buf_set_name, buf, "git://" .. ref .. "/" .. path)
-    return buf
-end
-
 ---Build a buffer holding the file's content at a given blob, named after the
 ---commit ref it corresponds to (so the name lines up with `git log` output
 ---instead of an opaque blob hash).
@@ -100,7 +87,10 @@ end
 ---@return integer
 local function blob_buf(worktree, blob, path, ref)
     if is_zero(blob) then
-        return empty_buf(ref, path)
+        return diff.empty_buf({
+            name = "git://" .. ref .. "/" .. path,
+            bufhidden = "hide",
+        })
     end
     ---@cast blob string
     local buf = diff.git_show_blob(worktree, blob)