Enforce nesting limit in scanner#329
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MAX_NESTING_LEVEL was only checked in parser.c, so yaml_parser_scan() callers had no depth protection. Deep flow nesting caused O(n²) CPU via simple_keys scanning. Add the limit check in the scanner's yaml_parser_increase_flow_level() and a test.
Address PR review: also enforce MAX_NESTING_LEVEL in yaml_parser_roll_indent() for block nesting, not just flow nesting. Add block nesting test.
Ensure block indent depth and flow level are checked together against MAX_NESTING_LEVEL, not independently. This prevents exceeding the intended limit with e.g. 1000 block indents + 1000 flow levels. Mirrors the approach already used in parser.c.
Add test-nesting binary and DartConfiguration.tcl (generated by cmake CTest).
The scanner now checks combined block+flow nesting depth, making the parser-level checks redundant. Remove them and unify the flow-level check to use STACK_LIMIT for consistency with roll_indent.
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MAX_NESTING_LEVEL was only checked in parser.c, so yaml_parser_scan() callers had no depth protection. Deep flow nesting caused O(n²) CPU via simple_keys scanning. Add the limit check in the scanner's
yaml_parser_increase_flow_level() and a test.