evert: remove experimental my.dash.board PWA virtual host

Reverts the experimental feature that attempted to serve the dashboard
via a local HTTP server registered as a hardcoded `my.dash.board` virtual
host, intended to satisfy Chrome's PWA "secure origin" installability
requirement. The approach caused proxy connection errors and file-not-found
issues that were not worth resolving.

Removed: native-host/dashboard-server.js, native-host/test-chain.mjs
Reverted: startup.js, message-router.js, virtual-hosts.js, index.js,
          build-distributable.js, extension/pages/virtual-hosts.js,
          CI workflows (ci.yml, release.yml)

.gitea/workflows/release.yml

@@ -71,13 +71,6 @@ jobs:
             exit 1
           fi
 
-          if echo "$OUTPUT" | grep -q "\[dashboard-server\] listening on"; then
-            echo "PASS: dashboard server started (my.dash.board virtual host registered)"
-          else
-            echo "FAIL: dashboard server did not start — bundle assets may be missing"
-            exit 1
-          fi
-
       - name: List release artifacts
         run: |
           echo "=== releases/ ==="