New Features:
- Add complete mix_task_chat example demonstrating SDK integration
- mix chat: Streaming responses with interactive multi-turn conversations
- mix ask: Simple query task for scripting with quiet/JSON output modes
- Comprehensive README tutorial with architecture diagrams and code examples

Documentation:
- Update main README with prominent Mix Task Example section
- Add examples to ExDoc sidebar with dedicated Examples group
- Include mix_task_chat in hex package distribution

Dependencies:
- Update credo 1.7.12 to 1.7.15
- Update dialyxir 1.4.5 to 1.4.7
- Update erlexec 2.2.0 to 2.2.2
- Update ex_doc 0.38.2 to 0.39.3
- Update supertester 0.4.0 to 0.5.0

Bug Fixes:
- Remove invalid timeout option from System.cmd/3 call in DebugMode
- Use proper boolean guards with 'and' instead of '&&' for nil safety
- Replace length(list) > 0 with list != [] for efficiency
- Fix alias ordering to be alphabetical in Streaming and test modules
- Migrate deprecated preferred_cli_env to def cli block
- Suppress intentional struct field count warning in Options module