fix(ci): use proper deep compare

lua/cp/highlight.lua

@@ -97,8 +97,9 @@ function M.parse_git_diff(diff_output)
           table.insert(all_highlights, highlight)
         end
       elseif not line:match('^%-') and not line:match('^\\') then -- Skip removed lines and "\ No newline" messages
-        -- Unchanged line
-        local parsed_line, line_highlights = parse_diff_line(line)
+        -- Unchanged line - remove leading space if present
+        local clean_line = line:match('^%s') and line:sub(2) or line
+        local parsed_line, line_highlights = parse_diff_line(clean_line)
         table.insert(content_lines, parsed_line)
 
         -- Set line numbers for any highlights (shouldn't be any for unchanged lines)

spec/highlight_spec.lua

@@ -100,8 +100,11 @@ index 1234567..abcdefg 100644
 
       highlight.apply_highlights(1, highlights, 100)
 
-      local call_args = mock_extmark.calls[1].vals
-      assert.equals('CpDiffAdded', call_args[4].hl_group)
+      assert.stub(mock_extmark).was_called_with(1, 100, 0, 0, {
+        end_col = 5,
+        hl_group = 'CpDiffAdded',
+        priority = 100,
+      })
       mock_extmark:revert()
       mock_clear:revert()
     end)