feat: Add error recovery system

[rlch]

Implements error recovery inspired by Chumsky's recovery system in Rust, addressing GitHub issue #342.

Features:

• RecoveryStrategy interface with multiple implementations:
  • SkipUntil/SkipPast: classic panic-mode recovery
  • SkipThenRetryUntil: skip and retry parsing
  • NestedDelimiters: balanced delimiter recovery
  • TokenSyncStrategy: sync on token types
  • CompositeStrategy: try multiple strategies in order
• RecoveryError type for multi-error reporting
• ParseOptions: Recover(strategies...) and MaxRecoveryErrors(n)

The implementation allows parsers to continue after errors, collecting multiple errors and producing partial ASTs - useful for IDE integration, linters, and comprehensive error messages.

Includes comprehensive test coverage (100% on new code) and example at _examples/recovery/.