[TASK] ConfigLoader (TOML)

[kirich1409]

Context

Loads ~/.config/devsweep/config.toml + rules.d/*.toml. If a new dependency is needed (e.g., TOMLKit), record choice in an ADR; user approval required before adding to Package.swift.

Acceptance criteria

• Loads main config + rules.d files.
• Dependency choice documented in docs/adr/ (if any new lib is added).
• Config file created with 0600 permissions on first write.

Files to touch (estimate)

best-effort estimate; agent refines during implementation

Implementation notes

n/a

Dependencies

None.

Safety checklist

See .github/ISSUE_TEMPLATE/task.yml — tick applicable invariants in the issue if any destructive path is touched.

Definition of Done

• Acceptance criteria satisfied and verifiable
• Tests added or updated
• No build / lint / test regressions
• Self-review against research-report invariants
• Code review approved