Root cause of 84% reweave PR rejection rate: claim titles with colons
(e.g., "COAL: Meta-PoW: The ORE Treasury Protocol") written as bare
YAML list items, causing yaml.safe_load to fail during merge.
Three changes:
1. frontmatter.py: _yaml_quote() wraps colon-containing values in double quotes
2. reweave.py: _write_edge_regex uses _yaml_quote for new edges
3. merge.py: skip individual files with parse failures instead of aborting entire PR
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>