Lift superpowers:code-reviewer agent into the requesting-code-review skill

The plugin had a single named agent (`agents/code-reviewer.md`) used by
two skills, while every other reviewer/implementer subagent in the repo
is dispatched as `general-purpose` with the prompt template living
alongside its skill. That asymmetry had no upside and several costs:

- Two sources of truth for the code review checklist (the agent file
  and `requesting-code-review/code-reviewer.md`), both drifting
  independently.
- `Codex` users could not use the named agent directly; the codex-tools
  reference doc had a workaround section explaining how to flatten the
  named agent into a `worker` dispatch.
- No third-party reliance on `superpowers:code-reviewer` inside this
  repo.

Changes:
- Merge `agents/code-reviewer.md` (persona + checklist) and
  `skills/requesting-code-review/code-reviewer.md` (placeholder
  template) into a single self-contained Task-dispatch template,
  matching the shape of `implementer-prompt.md`,
  `spec-reviewer-prompt.md`, etc.
- Update `skills/requesting-code-review/SKILL.md` and
  `skills/subagent-driven-development/code-quality-reviewer-prompt.md`
  to dispatch `Task (general-purpose)` instead of the named agent.
- Drop the now-obsolete "Named agent dispatch" workaround sections from
  `codex-tools.md` and `copilot-tools.md` — superpowers no longer ships
  any named agents, so those instructions documented nothing.
- Delete `agents/code-reviewer.md` and the empty `agents/` directory.

Tier 3 coverage for the change: a new behavioral test
`tests/claude-code/test-requesting-code-review.sh` plants real bugs
(SQL injection, plaintext password handling, credential logging) into
a tiny project, runs the actual `requesting-code-review` skill against
the working tree, and asserts the dispatched reviewer flags every
planted issue at Critical/Important severity and refuses to approve
the diff.

Verified end-to-end on this branch:
- The new test passes (5/5 assertions; reviewer caught all planted
  bugs and several others).
- The existing SDD integration test still passes (7/7 subagents
  dispatched, all as `general-purpose`; spec compliance still
  rejects extra features; produced code is correct).
- Session JSONLs confirm zero remaining `superpowers:code-reviewer`
  dispatches anywhere in the SDD pipeline.

skills/requesting-code-review/SKILL.md

@@ -5,7 +5,7 @@ description: Use when completing tasks, implementing major features, or before m
 
 # Requesting Code Review
 
-Dispatch superpowers:code-reviewer subagent to catch issues before they cascade. The reviewer gets precisely crafted context for evaluation — never your session's history. This keeps the reviewer focused on the work product, not your thought process, and preserves your own context for continued work.
+Dispatch a code reviewer subagent to catch issues before they cascade. The reviewer gets precisely crafted context for evaluation — never your session's history. This keeps the reviewer focused on the work product, not your thought process, and preserves your own context for continued work.
 
 **Core principle:** Review early, review often.
 
@@ -29,16 +29,15 @@ BASE_SHA=$(git rev-parse HEAD~1)  # or origin/main
 HEAD_SHA=$(git rev-parse HEAD)
 ```
 
-**2. Dispatch code-reviewer subagent:**
+**2. Dispatch code reviewer subagent:**
 
-Use Task tool with superpowers:code-reviewer type, fill template at `code-reviewer.md`
+Use Task tool with `general-purpose` type, fill template at `code-reviewer.md`
 
 **Placeholders:**
-- `{WHAT_WAS_IMPLEMENTED}` - What you just built
+- `{DESCRIPTION}` - Brief summary of what you built
 - `{PLAN_OR_REQUIREMENTS}` - What it should do
 - `{BASE_SHA}` - Starting commit
 - `{HEAD_SHA}` - Ending commit
-- `{DESCRIPTION}` - Brief summary
 
 **3. Act on feedback:**
 - Fix Critical issues immediately
@@ -56,12 +55,11 @@ You: Let me request code review before proceeding.
 BASE_SHA=$(git log --oneline | grep "Task 1" | head -1 | awk '{print $1}')
 HEAD_SHA=$(git rev-parse HEAD)
 
-[Dispatch superpowers:code-reviewer subagent]
-  WHAT_WAS_IMPLEMENTED: Verification and repair functions for conversation index
+[Dispatch code reviewer subagent]
+  DESCRIPTION: Added verifyIndex() and repairIndex() with 4 issue types
   PLAN_OR_REQUIREMENTS: Task 2 from docs/superpowers/plans/deployment-plan.md
   BASE_SHA: a7981ec
   HEAD_SHA: 3df7661
-  DESCRIPTION: Added verifyIndex() and repairIndex() with 4 issue types
 
 [Subagent returns]:
   Strengths: Clean architecture, real tests