init: @trentuna/pi-openspec — 13-tool OpenSpec extension for pi

- extensions/openspec.ts — 13 tools wrapping openspec CLI
- skills/openspec/SKILL.md — full workflow guidance for agents
- package.json — pi manifest with pi-package keyword, @trentuna scope
- README.md — comprehensive: install, all 13 tools, quick-start, workflow
- LICENSE — MIT
- .gitignore

Adapted from a-team/extensions/openspec.ts (Hannibal, session 135).
Standalone package so any trentuna member can: pi install git:http://localhost:3001/trentuna/pi-openspec.git

package.json

@@ -0,0 +1,20 @@
+{
+  "name": "@trentuna/pi-openspec",
+  "version": "0.1.0",
+  "description": "OpenSpec pi extension — spec-driven development workflow for pi agent sessions",
+  "keywords": ["pi-package", "openspec", "spec-driven", "ai-agents", "trentuna"],
+  "author": "Trentuna <ludo@trentuna.com>",
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "http://localhost:3001/trentuna/pi-openspec.git"
+  },
+  "homepage": "https://trentuna.com",
+  "pi": {
+    "extensions": ["./extensions"],
+    "skills": ["./skills"]
+  },
+  "engines": {
+    "node": ">=18.0.0"
+  }
+}