fix(output_window): avoid shifting folds when inserting at their boundary

shift_folds previously used >= which moved fold ranges that started or ended exactly at
the insertion line. This caused folds to expand when inserting after their end. Use strict
'>' comparisons and add a unit test to ensure folds remain unchanged when inserting after
a fold's end.

This should fix questions not displaying at the end of a fold

Author: sudo-tee

lua/opencode/ui/output_window.lua

@@ -399,13 +399,13 @@ function M.shift_folds(start_line, delta)
   end
 
   for _, range in ipairs(folds) do
-    if range.from >= start_line then
+    if range.from > start_line then
       range.from = range.from + delta
       if delta < 0 then
         range.from = math.max(start_line, range.from)
       end
     end
-    if range.to >= start_line then
+    if range.to > start_line then
       range.to = range.to + delta
       if delta < 0 then
         range.to = math.max(start_line, range.to)

tests/unit/output_window_spec.lua

@@ -164,6 +164,16 @@ describe('output_window.setup', function()
 
     assert.equals(1, foldclosed)
   end)
+
+  it('does not expand a fold when inserting after its end', function()
+    output_window.setup({ output_buf = buf, output_win = win })
+    output_window.set_folds({ { from = 1, to = 3 } })
+
+    output_window.shift_folds(3, 4)
+
+    local folds = vim.api.nvim_buf_get_var(buf, 'opencode_folds')
+    assert.same({ { from = 1, to = 3 } }, folds)
+  end)
 end)
 
 describe('output_window extmarks', function()