Optimize string building in decodeUtf8_, slugify, parseRaw_, processCode_, and processBold_ by accumulating parts in a list and joining once, avoiding repeated string allocation. In HttpResponse constructor, precompute a normalized headers map for O(1) case-insensitive header lookups instead of linear scan. Simplify Json.stringify indent generation using string repetition operator.
Add new pexpect module for process spawning and interaction, including Spawn class with expect, sendline, and timeout handling. Introduce yaml module for YAML parsing with support for nested structures, lists, and data types. Extend jinja template engine with brace tokenization and FromImportNode for macro imports across templates. Register all new foreign functions in modules.c and include generated demo scripts.
