[DOCS] Restore dev-version banner gate after VitePress migration (#2305)

The VuePress->VitePress migration replaced the `themeConfig.mode === 'dev'`
gate with a heuristic on `site.title`. CI overrides version with a short
SHA (dev) or git tag (prod), so the title never contains "edge"/"dev" and
the banner never renders on live deploys. Surface `meta.mode` in
`themeConfig` and check it directly, mirroring the original behaviour.

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

docs/.vitepress/config.mts

@@ -32,6 +32,12 @@ export default defineConfig({
   },
   themeConfig: {
     siteTitle: 'OpenMQTTGateway',
+    // @ts-expect-error custom fields consumed by index.md to render the dev-version banner
+    mode: meta.mode,
+    // @ts-expect-error
+    version: meta.version,
+    // @ts-expect-error
+    repo: meta.theme_config_repo,
     nav: commonNav,
     socialLinks: [
       { icon: 'github', link: `https://github.com/${meta.theme_config_repo}` }

docs/index.md

@@ -1,12 +1,19 @@
 <script setup>
 import { useData } from 'vitepress'
-const { site } = useData()
-const isDev = site.value.title?.includes('edge') || site.value.title?.includes('dev')
+import { computed } from 'vue'
+const { theme } = useData()
+const isDev = theme.value.mode === 'dev'
+const version = theme.value.version
+const commitUrl = computed(() =>
+  theme.value.repo && version
+    ? `https://github.com/${theme.value.repo}/commit/${version}`
+    : null
+)
 </script>
 
 <div v-if="isDev" class="warning custom-block">
 <p class="custom-block-title">Development Version</p>
-<p>This is the edge version of the documentation. It is under active development and may contain bugs, incomplete features, or breaking changes. Use it at your own risk.</p>
+<p>This is the edge version of the documentation, built from commit <a v-if="commitUrl" :href="commitUrl"><code>{{ version }}</code></a><code v-else>{{ version }}</code>. It is under active development and may contain bugs, incomplete features, or breaking changes. Use it at your own risk.</p>
 </div>
 
 OpenMQTTGateway aims to unify various technologies and protocols into a single firmware. This reduces the need for multiple physical bridges and streamlines diverse technologies under the widely-used [MQTT](http://mqtt.org/) protocol.