refactor(plugin)!: ship as a Claude Code plugin, one dir link per harness

Skills move to skills/<name>/SKILL.md and the repo gains both manifests, so
it is now a marketplace hosting exactly one plugin whose root is the repo
root (source: "."). Claude Code installs it from git; no symlinks involved.

Why: install.sh wired the library into every consuming repo as an ABSOLUTE
symlink to $CHECKOUT_DIR. The checkout moved three times, most recently when
local-dev@1966d5a dropped the embedded .skills/ copy, and nothing migrated
the links — 243 dangling links across 12 repos, hidden from git by the
**/.claude/skills/ ignore rule. Worse, ~/dev spans two path roots
(/Users/mathias on the iCloud-shared Macs, /home/mathias on koala), so an
absolute link stored there is broken on one side by construction. Re-running
the installer cannot fix that; only removing the mechanism can.

install.sh keeps the harnesses with no plugin system and drops from 42 links
per harness to one directory link, via the convergent ~/.agents/skills
convention that Pi and OpenCode both read:

  ~/.agents/skills          -> $CHECKOUT_DIR/skills
  ~/.config/crush/skills    -> ~/.agents/skills
  ~/.config/opencode/skills -> ~/.agents/skills

wire_claude_repo is deleted outright rather than gated behind a flag — on a
mixed-root fleet it cannot be made correct. Antigravity and Vibe targets go
too; both unused. CHECKOUT_DIR keeps its host-local default deliberately:
pointing it into ~/dev would put a git working tree inside iCloud with two
concurrent writers.

Taskfile drops five near-identical wiring loops (they had already drifted)
and delegates to install.sh. `task check` gains frontmatter validation, a
stray-root-entry gate, and manifest/tag version parity — the loose
secret-hygiene.md sat unloadable for months because nothing checked layout.

Verified: claude plugin validate . passes clean; a probe skill loaded as
skills:zzprobe through --plugin-dir; task check green at 42 skills.

Refs: #23
Bump-Type: minor

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BeAp5LTscnz2W7Ubt4eJ6m

skills/superpowers-using-superpowers/references/codex-tools.md

@@ -0,0 +1,59 @@
+# Codex Tool Mapping
+
+Skills use Claude Code tool names. When you encounter these in a skill, use your platform equivalent:
+
+| Skill references | Codex equivalent |
+|-----------------|------------------|
+| `Task` tool (dispatch subagent) | `spawn_agent` (see [Subagent dispatch requires multi-agent support](#subagent-dispatch-requires-multi-agent-support)) |
+| Multiple `Task` calls (parallel) | Multiple `spawn_agent` calls |
+| Task returns result | `wait_agent` |
+| Task completes automatically | `close_agent` to free slot |
+| `TodoWrite` (task tracking) | `update_plan` |
+| `Skill` tool (invoke a skill) | Skills load natively — just follow the instructions |
+| `Read`, `Write`, `Edit` (files) | Use your native file tools |
+| `Bash` (run commands) | Use your native shell tools |
+
+## Subagent dispatch requires multi-agent support
+
+Add to your Codex config (`~/.codex/config.toml`):
+
+```toml
+[features]
+multi_agent = true
+```
+
+This enables `spawn_agent`, `wait_agent`, and `close_agent` for skills like `dispatching-parallel-agents` and `subagent-driven-development`.
+
+Legacy note: Codex builds before `rust-v0.115.0` exposed spawned-agent
+waiting as `wait`. Current Codex uses `wait_agent` for spawned agents. The
+`wait` name now belongs to code-mode `exec/wait`, which resumes a yielded exec
+cell by `cell_id`; it is not the spawned-agent result tool.
+
+## Environment Detection
+
+Skills that create worktrees or finish branches should detect their
+environment with read-only git commands before proceeding:
+
+```bash
+GIT_DIR=$(cd "$(git rev-parse --git-dir)" 2>/dev/null && pwd -P)
+GIT_COMMON=$(cd "$(git rev-parse --git-common-dir)" 2>/dev/null && pwd -P)
+BRANCH=$(git branch --show-current)
+```
+
+- `GIT_DIR != GIT_COMMON` → already in a linked worktree (skip creation)
+- `BRANCH` empty → detached HEAD (cannot branch/push/PR from sandbox)
+
+See `using-git-worktrees` Step 0 and `finishing-a-development-branch`
+Step 1 for how each skill uses these signals.
+
+## Codex App Finishing
+
+When the sandbox blocks branch/push operations (detached HEAD in an
+externally managed worktree), the agent commits all work and informs
+the user to use the App's native controls:
+
+- **"Create branch"** — names the branch, then commit/push/PR via App UI
+- **"Hand off to local"** — transfers work to the user's local checkout
+
+The agent can still run tests, stage files, and output suggested branch
+names, commit messages, and PR descriptions for the user to copy.