Add public read-only demo at /demo without account.

Let visitors explore ship data, crew, and sample log entries from the login page, with onboarding tour support and a fix for GPS track rendering when fileType is missing.

Co-authored-by: Cursor <cursoragent@cursor.com>

client/package-lock.json

@@ -36,6 +36,9 @@
         "typescript-eslint": "^8.59.2",
         "vite": "^8.0.12",
         "vite-plugin-pwa": "^1.3.0"
+      },
+      "optionalDependencies": {
+        "@rolldown/binding-linux-x64-gnu": "^1.0.2"
       }
     },
     "node_modules/@apideck/better-ajv-errors": {
@@ -2096,7 +2099,6 @@
       "cpu": [
         "x64"
       ],
-      "dev": true,
       "license": "MIT",
       "optional": true,
       "os": [