General-purpose Rust runtime with ops, extensions, resource table, event loop, and memory optimization.

• MontrsRuntime — main runtime struct managing extensions, ops, and event loop
• OpState — TypeMap for extension state (stores one value per type)
• RuntimeExtension — pluggable extension with ops, state init, and lifecycle hooks
• OpDecl — typed operation declaration (sync/async, with/without JSON input)
• ResourceTable — typed handles identified by ResourceId
• EventLoop — tokio-based async task management
• ModuleLoader — trait for loading Rust/WASM modules
• Arena — O(1) bump allocator for high-throughput temporary data
• TaggedValue — NaN-boxed 64-bit value representation (int, float, bool, ptr, null)
• BitField — packed multi-field structs in a single u64

The montrs_ext module provides a MontRS-specific runtime extension with ops for:

• montrs.ping — health check
• montrs.resource_count — count of resources in the resource table
• montrs.sleep_ms — async sleep (for testing)