feat: add videodb media index with Docker stack

- Add videodb PHP/MySQL media collection manager (Blu-ray, DVD, CD)
- Dockerfile: PHP 8.1 + Apache with GD/mysqli/exif extensions
- docker-compose.yml: app on port 6761 + MySQL 8.0 with health checks
- docker-entrypoint.sh: auto-generates config.inc.php from env vars,
  waits for MySQL, initializes DB schema idempotently
- init-db.php: CLI schema installer using app's own prefix_query() logic
- Persistent volumes for DB, cache, and cover images

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

videodb/templates/elegant/login.tpl

@@ -0,0 +1,54 @@
+{*
+  Login page
+  $Id: login.tpl,v 1.5 2005/06/04 16:59:36 andig2 Exp $
+*}
+
+<!-- {$smarty.template} -->
+
+<div id="topspacer"></div>
+
+<div id="content">
+
+<div id="contentlogin">
+    <br/>
+    <p class="center">{$lang.enterusername}</p>
+
+    <form action="login.php" id="login" method="post">
+        <input type="hidden" value="{$refer}" name="refer"/>
+
+        <table class="center">
+        <tr>
+            <td>{$lang.username}:</td>
+            <td><input type="textbox" id="username" name="username"/></td>
+        </tr>
+        <tr>
+            <td>{$lang.password}:</td>
+            <td><input type="password" name="password"/></td>
+        </tr>
+        <tr>
+            <td colspan="2"><input type="checkbox" name="permanent" id="permanent" value="1" /><label for="permanent">{$lang.stayloggedin}</label></td>
+        </tr>
+
+        <tr>
+            <td colspan="2" class="center">
+                <input type="submit" class="button" value="{$lang.login}" />
+            </td>
+        </tr>
+        </table>
+    </form>
+
+    {if $error}
+        <p>{$error}</p>
+    {/if}
+    <br/>
+</div>
+<!-- /contentlogin -->
+
+</div>
+<!-- /content -->
+
+<script language="JavaScript" type="text/javascript">
+// <!--
+    document.forms['login'].username.focus();
+// -->
+</script>