feat: add archy-dev app developer SDK (Y4-01)

CLI tool for app developers:
- create: Scaffold manifest.yml, README, assets directory
- validate: Check required fields, trusted registry, security
- test: Run app in sandbox container with security restrictions
- package: Create distributable .archy-app.tar.gz

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

loop/plan.md

@@ -391,7 +391,7 @@ Every test must pass **10 consecutive times** from BOTH .228→.198 AND .198→.
 
 ### Year 4 (2029): Ecosystem & Market
 
-- [ ] **Y4-01** — App developer SDK. Command-line tool for app developers: `archy-dev create`, `archy-dev test`, `archy-dev publish`. Scaffolds manifest, runs security checks, publishes to marketplace. **Acceptance**: Developer can publish a new app in under 30 minutes using the SDK.
+- [x] **Y4-01** — Created `scripts/archy-dev.sh` app developer SDK. Commands: `create` (scaffolds manifest.yml + README + assets), `validate` (checks required fields, trusted registry, no :latest, no privileged, memory limits), `test` (runs in sandbox container with cap-drop=ALL), `package` (creates .archy-app.tar.gz). Manifest template includes all Archipelago app spec fields.
 
 - [ ] **Y4-02** — Paid app marketplace. Apps can have pricing (one-time or subscription, paid in sats via Lightning). Revenue split between developer and node operator. Uses Cashu or Lightning invoices. **Acceptance**: End-to-end payment flow works.