sdd-execute-tasklisted

# Execute an SDD task 1. Resolve one `tasks/prd-[slug]/task_[num].md`. Require the PRD, TechSpec, and feature manifest. Read stable sources once per version in PRD, TechSpec, task order; consult state afterward. Confirm completed dependencies and a pending task. A task in `done/` is only reported. **Output:** exact contract, satisfied dependencies, and identified write scope. 2. Read local instructions and only skills relevant to the change. Inspect worktree, callers, and affected tests; preserve pre-existing changes. Map every acceptance item to implementation and evidence. **Output:** known change points; source or write conflicts returned to the caller before mutation. 3. Implement the smallest coherent change and behavior tests proportional to risk. Mark subtasks only with evidence. Edit only assigned files and the task itself; reserve manifest and moves for the caller. **Output:** implementation limited to the contract, with no global state changed. 4. Apply the TechSpec profile. In desktop C#/.NET, omit E2E even when legacy commands include it: select projects/filters without E2E and record the divergence. Preserve acceptance with relevant unit, integration, and manual scripts; unexecuted manual work remains pending. When available, use `dotnet-efficient-validation` for runner and build reuse. Run checks required by the diff; reuse evidence only from the same code, configuration, and environment. Zero tests or listing are not success. Record pre-existing fa