docs(index): rewrite "Wiring into tools" for the repo-native installer

The index still described local-dev's old wire-skills.sh / ~/dev/.skills
mechanism. This repo is now the canonical home; wiring is `task install`
(claude global+repo, crush, antigravity, vibe) or the curl|bash install.sh.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

SKILLS_INDEX.md

@@ -45,18 +45,21 @@ This index lists all available engineering skills. Load the full SKILL.md on dem
 
 ## Wiring into tools
 
-The canonical home is `~/dev/.skills/`. Per-tool surfacing is handled by
-`~/dev/.context/wire-skills.sh`:
+This repo **is** the canonical home. Clone it (e.g. to `~/dev/skills`) and run
+`task install` — or the one-shot `curl -fsSL .../install.sh | bash` — to wire
+every skill into each harness. Per-skill symlinks, idempotent:
 
-- **Claude Code** — each git repo under `~/dev/` gets a `<repo>/.claude/skills`
-  symlink pointing at `~/dev/.skills/`. The symlink is excluded by
-  `**/.claude/skills` in `~/.config/git/ignore`, so it never lands in commits.
-- **Crush** — per-skill symlinks under `~/.config/crush/skills/<name>`, added
-  alongside existing entries (e.g., `mstack/*`). Skills already present as
-  real directories or non-canonical symlinks are preserved.
+- **Claude Code (global)** — `~/.claude/skills/<name>` → `<repo>/<name>`.
+- **Claude Code (per-repo)** — `<repo>/.claude/skills/<name>` when `task install`
+  is run inside another git repo (excluded via `~/.config/git/ignore`).
+- **Crush** — `~/.config/crush/skills/<name>`.
+- **Antigravity** — `~/.gemini/antigravity/skills/<name>`.
+- **Mistral Vibe** — `~/.vibe/skills/<name>.md` → `<repo>/<name>/SKILL.md`
+  (flat `.md` layout).
 
-Run `bash ~/dev/.context/wire-skills.sh --dry-run` to preview, then drop the
-flag to apply. The script is idempotent.
+Individual targets are also runnable: `task install:claude:global`,
+`install:crush`, `install:antigravity`, `install:vibe`. `task update` pulls the
+canonical checkout then re-wires.
 
 ## Skill Relationships