Refactor direct source-driven automation flow

[chubes4]

Summary

• remove more planner-era naming and indirection by renaming the source orchestration layer from planner to sources
• align refactor source execution with the direct model: collect edits from existing audit/lint/test reports and gate --from writes only with manual_only
• clean up the leftover guard-shell plumbing and cached-audit test setup around the source orchestration path

Testing

• cargo test commands::refactor::tests --bin homeboy
• cargo test core::refactor::plan::sources --lib
• cargo test core::refactor --lib
• cargo test core::code_audit::report --lib