[Bug]: App implementation inconsistencies across stateful apps in pas/apps/

[deepakn97]

Bug Description

Different stateful app implementations in pas/apps/ use inconsistent patterns for state transitions, argument extraction, class definitions, metadata access, and back navigation. This creates maintenance burden and makes it harder to implement new apps consistently.

Steps to Reproduce

1. Compare dispatch patterns across apps: contacts uses match statements, email uses isinstance checks, cab uses if/elif chains, note uses dynamic method lookup, messaging uses inline logic
2. Compare event args extraction: some apps use action.resolved_args or action.args, others use action.args or {}, others use getattr(action, "args", {})
3. Compare class definition styles: most use regular classes, note uses dataclass, shopping uses custom signature

Expected Behavior

All stateful apps should follow a consistent pattern for:

• State transition dispatch (suggest state-first isinstance for complex apps, match for simple apps)
• Event args extraction (always use action.resolved_args or action.args)
• Class definition (regular classes, not dataclasses)
• Metadata null checks (always check event.metadata before accessing return_value)
• Back navigation handling

Actual Behavior

5 different dispatch patterns, 6 different args extraction patterns, mixed class definition styles, and inconsistent null checking across the 9 stateful apps.

Component

Apps

Environment

- OS: macOS 26.3.1
- Python version: 3.12.0
- PAS version/commit: main branch
- Installed via: uv

Minimal Reproducible Example

Relevant Logs

Additional Context

Recommendations:

1. Pick one dispatch pattern per complexity level
2. Standardize args extraction to action.resolved_args or action.args
3. Standardize class definitions as regular classes
4. Always null-check metadata before accessing return_value
5. Document chosen patterns for future app implementations

Pre-submission Checklist

• I have searched existing issues to ensure this is not a duplicate
• I have included a minimal reproducible example (if applicable)
• I have included relevant logs and error messages