Refactor safety_check() - Separate validation from enforcement

[flyingrobots]

Part of SRP Refactoring (Priority 2: CLI Layer)

Current Problem

safety_check() in src/cli/main.c combines path checking, git config, error display, and enforcement in one function.

Refactoring Plan

Split into focused functions:

• validate_working_directory() - Path validation only
• check_remote_safety() - Remote URL validation
• enforce_safety_policy() - Decision logic only
• report_safety_violation() - Error formatting/display

Acceptance Criteria

• Each validation step isolated
• Policy decisions separated from checks
• Error reporting extracted
• Easier to test each validation
• Clear separation of concerns
• Improved error messages

Technical Notes

• Consider policy configuration
• Make validators reusable
• Return structured error information

Related to SRP_REFACTORING_PLAN.md Priority 2.1