Code Quality Improvements

[vertti]

This PR improves code quality by removing dead code, improving Python idioms, refactoring large functions, and enabling comprehensive linting with ALL ruff rules.

Changes Made

Remove Dead Code & Clutter

• Removed 2 unused _build_task_feature_choices functions and their tests
• Inlined _get_event_type_style helper
• Removed decorative rocket emoji from welcome message (per CLAUDE.md)
• Removed 5 obvious/redundant comments
• Impact: -50 lines of dead code

More Pythonic Patterns

• Simplified AWS client creation using ternary operator (4 functions)
• Replaced nested list comprehension with readable for-loop in service/service.py:29-39
• Removed unnecessary lambda wrapper in container/container.py:133
• Impact: Clearer, more idiomatic Python

Better Code Organization

• Extracted action mappings to module-level constants (_CONTAINER_ACTIONS, _TASK_ACTIONS)
• Extracted change type display config to _CHANGE_TYPE_DISPLAY constant in task/ui.py
• Reduced _handle_task_features from 35→13 lines
• Impact: More maintainable, easier to extend

Improved Naming

• _create_service_event → _parse_service_event (parsing vs creating)
• _list_tasks_paginated → _list_tasks_by_status (more descriptive)
• Updated corresponding test names
• Impact: Clearer intent

Enable ALL Ruff Rules (~200+ Additional Checks)

• Changed from 13 specific rules to ALL with sensible ignores
• Auto-fixed 120 violations (trailing commas, import sorting, etc.)
• Added ignores for 22 rules that don't fit CLI tool style
• Fixed formatter conflict (COM812)
• Impact: Comprehensive linting coverage