Add shared SDC app shell (SdcTopBar + ApiSettings + unified credentials)

Workstream D: a shared top bar for the SDC tool suite — app name (left), API
settings cog, and the suite app directory (grid) — composed on the existing
TopBar. Adds an ApiSettings dialog and sdc_api_key/sdc_api_endpoint credential
helpers (shared once across all tools, with legacy-key migration). lucide-react
becomes a peer dependency. Bump to 0.2.0.

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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@richiesnitch/ads3-design-system",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "type": "module",
   "repository": {
     "type": "git",
@@ -33,6 +33,7 @@
     "build-storybook": "storybook build"
   },
   "peerDependencies": {
+    "lucide-react": "^1.16.0",
     "react": "^19.0.0",
     "react-dom": "^19.0.0"
   },