Refactor AnyGen CLI for better state management

[manucian-official]

Refactor: CLI Architecture Optimization

Overview

This update delivers a focused internal refactor of the AnyGen CLI, improving structure, consistency, and maintainability without introducing any breaking changes.

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Highlights

• Centralized State Management
  Introduced AppContext as a single source of truth, replacing fragmented global variables.

• Unified Output Layer
  Standardized all outputs via a single handler, ensuring consistency across CLI and JSON modes.

• Normalized Error Handling
  Implemented a decorator-based approach for clean, predictable error reporting.

• Lazy Initialization
  Deferred session loading to reduce unnecessary I/O and improve startup performance.

• Reduced Duplication
  Abstracted repeated patterns, resulting in a leaner and more maintainable codebase.

• Simplified CLI Structure
  Streamlined command definitions for improved readability and usability.

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Design Principles

• Separation of Concerns
• Single Source of Truth
• Consistency Over Convenience
• Extensibility by Design

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Compatibility

• No breaking changes
• All existing commands remain intact
• Fully backward compatible

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Summary

This refactor strengthens the internal architecture, delivering a cleaner, more scalable foundation for future development while remaining completely transparent to end users.

[omerarslan0]

@manucian-official Same problem as #180. The AppContext dataclass is a fine idea (~10 lines), but the rest of the PR deletes 15 of ~20 commands with no replacement. That's not refactoring.

Keep all existing commands, fix the 4 bugs from #180 review, and submit only the state management change:

1. Rename json parameter to use_json — it shadows import json
2. Add @functools.wraps(func) to handle_error
3. Mask API key in config set output
4. Restore click.Choice validation on config set

Do not delete commands. Do not remove CLI options from task run. The AppContext refactor should be a zero-behavior-change commit.