Replace placeholder screenshot with real capabilities menu; bump to 0.2.1

screenshot-1.png is now an actual terminal capture of the skill's
welcome menu, showing the 14 tools grouped by category (Design &
Propose, Validate & Check, Strategy & Business, Knowledge Base,
ECAL Governance, SA Tools). Much more informative for the
marketplace preview than the generic placeholder.

Asset refresh — version bumped to 0.2.1 as promised in the admin
submission email.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.codex-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "oci-deal-accelerator",
-  "version": "0.2.0",
+  "version": "0.2.1",
   "description": "Oracle Cloud Infrastructure deal-acceleration toolkit: proposals, BOMs, cost estimates, diagrams, WA reviews, and reference-architecture search via a remote MCP server.",
   "author": {
     "name": "Diego Cabrera",