Rename project from Nexa to Osias

Renames the npm package (nexa-extension -> osias-extension), the
extension manifest name and Firefox gecko id
([email protected]), the internal runtime message-type
namespace and storage keys ('nexa:...' -> 'osias:...'), the
NexaMessage type, and all remaining Nexa branding in source comments,
UI copy, and CLAUDE.md to match the new osias.trade domain and the
osias-trade GitHub org.

No wire-protocol changes — purely internal naming plus user-facing
strings.

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Tn7uDYjTuZEbLPwpEiSCUw

wxt.config.ts

@@ -8,15 +8,15 @@ export default defineConfig({
   // Target Manifest V3 on both Chromium and Firefox (modern Firefox / Zen support it).
   manifestVersion: 3,
   manifest: {
-    name: 'Nexa',
+    name: 'Osias',
     description: 'Your blockchain powered agent to help with your trading emotions.',
     permissions: ['storage'],
-    // axiom.trade: the site adapter target. The other entry is the Nexa backend.
+    // axiom.trade: the site adapter target. The other entry is the Osias backend.
     host_permissions: ['https://axiom.trade/*', BACKEND_HTTP_URL + "/*"],
     browser_specific_settings: {
       gecko: {
         // Placeholder id for local/dev builds; replace before publishing to AMO.
-        id: 'nexa-extension@nexa-sol.dev',
+        id: 'osias-extension@osias.trade',
       },
     },
   },