Rewrite lazycommit for speed, cleaner architecture, and agent integration

[m7medVision]

Summary

Rewrite lazycommit to make it faster, cleaner, and easier to integrate with coding agents.

Why

Cuz I wanna to do it.

Goals

• Make CLI execution faster than it is today.
• Clean up the codebase with clearer package boundaries.
• Support agent-friendly usage through structured/non-interactive output.
• Make provider/config/git behavior easier to test and maintain.
• Keep existing supported CLI behavior unless there is a clear reason to change it.

Rewrite Direction

• Keep cmd focused on CLI definitions only.
• Move core workflows into separate app/use-case logic.
• Separate git, config, provider, output, and agent integration responsibilities.
• Add JSON/non-interactive output for agents.
• Reduce repeated git/config work and make provider calls cancellable.

Acceptance Criteria

• Common commands are measurably faster.
• Code structure is cleaner and easier to follow.
• Agent integration path exists.
• Main workflows have tests.
• go test ./... passes.