refactor(skills): remove workflows covered by Superpowers

Drop the debugging, implementation-planner, code-review, and
regression-verification skills so Superpowers owns these triggers without
competing descriptions. Focused domain skills remain.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

shared/skills/planning/implementation-planner/SKILL.md

@@ -1,19 +0,0 @@
----
-name: implementation-planner
-description: Use when requirements are understood but implementation needs multiple dependent steps, affected areas, risk handling, or coordinated verification. Produce a plan without making the changes.
----
-
-# Implementation Planner
-
-Use when an understood change has multiple dependent steps or meaningful coordination risk.
-
-## Workflow
-
-1. Restate the intended outcome and acceptance conditions without expanding the request.
-2. Identify the files, components, data contracts, or workflows likely to change. Confirm the repository's existing patterns before proposing new structure.
-3. Order work by dependency. Keep steps small enough to review and verify independently where possible.
-4. Call out decisions that affect compatibility, data, permissions, or external systems. Resolve routine reversible choices using repository conventions.
-5. Pair each substantial step with the cheapest useful verification.
-6. Keep the plan concise and omit speculative scaffolding, unrelated cleanup, and work that can safely wait.
-
-Return an actionable sequence with affected areas, risks, and checks. This skill plans only; do not implement the change.