A tiny mail-merge template engine

A bank in Johannesburg sends personalised letters. The letter template contains placeholders like {{ name | title }}. A placeholder starts at {{ and ends at the nearest following }} on the same line; a {{ without a closing }} on its line stays as plain text. The inserted text is never scanned again for placeholders.

Inside the braces, parts are separated by | and every part is trimmed of spaces. The first part is the variable name. Remaining parts are filters applied left to right: upper, lower, trim (strip spaces from both ends of the value), title (every space-separated word gets an upper-case first letter and lower-case rest) and default:TEXT. The default filter replaces the value by TEXT (trimmed) when the variable is missing or its value is empty or only spaces; later filters then work on that text. The other filters never change a missing variable. If after all filters a variable is still missing, the placeholder becomes <missing:name>.

Task: line 1 is K, then K lines key=value (split at the first =; the key is trimmed, the value is kept exactly as written, possibly empty). Then a line with M and M template lines. Print the rendered template lines.