chat: unify remaining formats to PEG grammar generation
- Port apriel-1-5, xiaomi-mimo, qwen3-coder-xml, kimi-k2, glm-4-5
to use parser.build_grammar() instead of build_grammar_xml_tool_call
- Remove build_grammar_xml_tool_call and make_gbnf_excluding functions
(no longer needed as all formats now use PEG for grammar generation)
- Remove optional() around closing tags in XML-style parsers
(not needed for streaming, was causing grammar mismatches)
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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
