📌 docs: Banner (#459)

* feat: add Banner system docs

* chore: cleanup old updates

Author: berry-13

pages/docs/configuration/_meta.ts

@@ -12,4 +12,5 @@ export default {
   azure: 'Azure OpenAI',
   docker_override: 'Docker Override',
   mod_system: 'Automated Moderation',
+  banner: 'Banner',
 }

pages/docs/configuration/banner.mdx

@@ -0,0 +1,104 @@
+---
+title: Banner
+description: Display announcements and notices to your users
+---
+
+# 📢 Banner
+
+Display important messages to all your users at the top of the app. Perfect for announcements, maintenance notices, or updates.
+
+<Callout type="info" title="Quick Overview">
+  - Only **one banner** can be active at a time
+  - Schedule banners to appear and disappear automatically
+  - Choose whether users can dismiss the banner or not
+  - Show banners to everyone, or only logged-in users
+</Callout>
+
+---
+
+## Creating a Banner
+
+Run this command to create or update a banner:
+
+```bash
+npm run update-banner
+```
+
+You'll be guided through a few simple prompts:
+
+```ansi
+--------------------------
+Update the banner!
+--------------------------
+Display From (Format: yyyy-mm-ddTHH:MM:SSZ, Default: now):
+> 2025-12-02T09:00:00Z
+
+Display To (Format: yyyy-mm-ddTHH:MM:SSZ, Default: not specified):
+> 2025-12-31T23:59:59Z
+
+Enter your message (Enter a single dot "." on a new line to finish):
+> 🎉 Welcome to LibreChat! Check out our new features.
+> .
+
+Is public (y/N):
+> n
+
+Is persistable (cannot be dismissed) (y/N):
+> n
+```
+
+<Callout type="tip" title="What do these options mean?">
+  - **Display From/To**: When the banner should appear and disappear. Leave empty for "now" and "forever"
+  - **Is public**: Show to visitors who aren't logged in (like on the login page)
+  - **Is persistable**: If yes, users can't dismiss the banner — use for important notices
+</Callout>
+
+---
+
+## Deleting a Banner
+
+```bash
+npm run delete-banner
+```
+
+You'll see the current banner and be asked to confirm before deleting.
+
+---
+
+## Example Banners
+
+<Tabs items={['Welcome Message', 'Maintenance Notice', 'Security Alert']}>
+  <Tabs.Tab>
+    A simple welcome message that users can dismiss:
+
+    ```bash
+    npm run update-banner "" "" "👋 Welcome to LibreChat!" "false" "false"
+    ```
+  </Tabs.Tab>
+  <Tabs.Tab>
+    A scheduled maintenance notice that can't be dismissed:
+
+    ```bash
+    npm run update-banner "2025-12-20T00:00:00Z" "2025-12-21T06:00:00Z" "⚠️ Scheduled maintenance on Dec 20th, 2-6 AM UTC" "true" "true"
+    ```
+  </Tabs.Tab>
+  <Tabs.Tab>
+    An urgent security notice visible to everyone:
+
+    ```bash
+    npm run update-banner "" "" "🔒 Please update your password by January 1st" "true" "true"
+    ```
+  </Tabs.Tab>
+</Tabs>
+
+---
+
+## Date Format
+
+Use this format for dates: `yyyy-mm-ddTHH:MM:SSZ`
+
+**Examples:**
+- `2025-12-25T09:00:00Z` → December 25, 2025 at 9:00 AM (UTC)
+- `2025-01-01T00:00:00Z` → January 1, 2025 at midnight (UTC)
+
+Leave the date empty to use the current time or no end date.