refactor(git): older-on-left placement, drop empty placeholders

lua/git/util.lua

@@ -62,22 +62,16 @@ local function setup_scratch(buf, opts)
     end
 end
 
----Build a read-only scratch buffer, optionally naming it. When `opts.name`
----is set and a loaded buffer with that name already exists, returns it
----instead of creating a duplicate.
----@param opts ow.Git.ScratchOpts?
----@return integer
-function M.empty_buf(opts)
-    opts = opts or {}
-    if opts.name then
-        local existing = vim.fn.bufnr(opts.name)
-        if existing ~= -1 and vim.api.nvim_buf_is_loaded(existing) then
-            return existing
-        end
+---Set a buffer's name and re-run filetype detection from it. Wrapped
+---in `pcall` because a buffer with that name may already exist (E95).
+---@param buf integer
+---@param name string
+function M.set_buf_name(buf, name)
+    pcall(vim.api.nvim_buf_set_name, buf, name)
+    local ft = vim.filetype.match({ buf = buf })
+    if ft then
+        vim.bo[buf].filetype = ft
     end
-    local buf = vim.api.nvim_create_buf(false, true)
-    setup_scratch(buf, opts)
-    return buf
 end
 
 ---Place a buffer in the current window or a new split per `split`.
@@ -96,7 +90,7 @@ function M.place_buf(buf, split)
     local win = vim.api.nvim_open_win(buf, true, {
         split = split or (vim.o.splitbelow and "below" or "above"),
     })
-    vim.cmd("clearjumps")
+    vim.cmd.clearjumps()
     return win
 end