chat: migrate glm_4_5 to modular PEG parser
Move GLM 4.5 tool call parsing to common/chat-syntax/glm-4-5.cpp.
Uses constructed PEG parser for XML-style format:
<tool_call>func_name<arg_key>key</arg_key><arg_value>value</arg_value></tool_call>
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
