feat: Enhance async state machine compilation with proper escape analysis

- Implement proper capture analysis with escape analysis to determine
  which variables need to be stored in the state machine struct
- Add CFG traversal for complex control flow handling when splitting
  functions at await points
- Extract local variables from code segments with type inference
- Use arena-allocated strings via InternedString::new_global for
  block labels and type names in state dispatch logic
- Build complete state dispatch with switch on current state and
  proper block handlers for each async state

Author: darmie