1.0.6

Add comprehensive test suite and improve memory management for pg_query_stack

Core improvements:

• Fix memory leaks by implementing proper cleanup with pg_stack_list_free_deep()
• Remove separate MemoryContext, use TopTransactionContext directly
• Add query length limit (MAX_QUERY_TEXT_LENGTH: 512KB) to prevent memory overflow
• Reduce MAX_QUERY_STACK_DEPTH from 1000 to 100 for better resource usage
• Add OOM handling with PG_TRY/PG_CATCH blocks
• Improve NULL safety checks throughout the code

Test suite additions:

• Add 14 regression tests covering all extension features
• Include automated test scripts (run_tests.sh, run_single_test.sh)
• Add TESTING.md documentation with detailed test descriptions