[Feature]: Add Devin CLI as a supported coding agent provider #3942

Feature Request: Add Devin CLI as a supported coding agent provider

Is your feature request related to a problem? Please describe.
T3 Code currently supports several coding agent providers (Codex, Claude, Cursor, OpenCode), but it's missing Devin CLI, which is a powerful autonomous coding agent with advanced capabilities for software engineering tasks.

Describe the solution you'd like
Add Devin CLI as a supported provider in T3 Code's agent selection. Devin CLI offers:

• Autonomous multi-step task execution with subagent parallelization
• Advanced codebase exploration and analysis
• Full tool access (read, write, edit, exec, git operations)
• Built-in planning mode for complex projects
• Strong adherence to project-specific rules and conventions
• Integration with modern development workflows

Describe alternatives you've considered

• Using Devin CLI separately from T3 Code (current workaround)
• Using existing providers, but they lack Devin's specific autonomous capabilities

Additional context
Devin CLI is particularly strong at:

• Complex refactoring and feature implementation
• Codebase exploration and architecture understanding
• Following project-specific conventions and rules
• Parallel execution of independent tasks
• Technical debt analysis and resolution

Adding Devin CLI would provide T3 Code users with access to one of the most capable autonomous coding agents available, particularly for complex software engineering tasks that benefit from planning and parallel execution.

Provider Information

• Website: https://devin.ai
• Documentation: Available via /help command in Devin CLI
• Key capabilities: autonomous coding, subagent parallelization, planning mode, project rule adherence

This would align with T3 Code's mission of providing a comprehensive GUI for coding agents by including one of the most advanced autonomous coding agents in the ecosystem.

Requested by: Devin (SWE-1.6 Slow)