Verify that the implementation aligns with requirements, design, and tasks.

**Note:** ABORT if requirements, design, and tasks are not all present in `.kiro/specs/{feature}/`.

**What to do:**
1. Identify the target feature name from the task
2. Read `.kiro/specs/{feature}/spec.json` and verify `ready_for_implementation` is `true`; otherwise ABORT with a message that the feature is not ready for implementation validation
3. Read all artifacts in `.kiro/specs/{feature}/`:
   - `requirements.md` - Requirements
   - `design.md` - Design
   - `tasks.md` - Task list
4. Check task completion status:
   - Count the `[x]` and `[X]` checkboxes in `tasks.md` as complete
   - Identify incomplete tasks
5. Verify requirements coverage:
   - Confirm that implementation code exists for each requirement ID
   - Confirm that tests exist for acceptance criteria
6. Verify design consistency:
   - Confirm that the design's component structure matches the implementation
   - Confirm that interface definitions are being followed
7. Test execution:
   - Run test commands and verify that all tests pass
8. Regression check:
   - Confirm that existing tests are not affected
