Route index.php and create_ticket_api.php through Database::getConnection() (#103, #104)

Both files opened their own raw new mysqli(...) connection instead of
using Database::getConnection(), missing the charset/timezone sync
every other connection gets. index.php's connection serves nearly all
non-API web traffic (dashboard, ticket view, ticket create) — any
NOW()/CURDATE()-based query through it used the DB server's default
session timezone instead of the app's configured TIMEZONE, and no
explicit utf8mb4 charset meant multi-byte characters typed into a
ticket via the non-JS POST fallback could get corrupted at write time.
create_ticket_api.php (the hwmonDaemon Bearer endpoint) had the same
timezone gap, risking created_at landing on the wrong 'day' relative
to every other ticket-creation path.

index.php's raw die("Connection failed: " . $conn->connect_error) also
leaked raw mysqli error text (host/user/failure reason) to any
unauthenticated visitor on a DB outage; it now logs via error_log()
and shows a generic message instead. create_ticket_api.php already
handled this correctly (JSON error + error_log, no leak) and needed no
behavior change there beyond the connection source.

Verified against real MariaDB: the new connection path reports the
configured -04:00 session time_zone and utf8mb4 charset, vs. SYSTEM
tz on the old raw-mysqli path; a simulated connection failure (bad
DB_NAME) confirmed only the generic message reaches the response body
while the raw driver error goes to error_log().

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Lhz7pGMaoTfL5sdYS5XiKv

index.php

@@ -5,6 +5,7 @@ require_once 'config/config.php';
 require_once 'middleware/SecurityHeadersMiddleware.php';
 require_once 'middleware/AuthMiddleware.php';
 require_once 'models/AuditLogModel.php';
+require_once 'helpers/Database.php';
 
 // Apply security headers early
 SecurityHeadersMiddleware::apply();
@@ -17,15 +18,12 @@ $requestPath = strtok($request, '?');
 
 // Create database connection for non-API routes
 if (!str_starts_with($requestPath, '/api/')) {
-    $conn = new mysqli(
-        $GLOBALS['config']['DB_HOST'],
-        $GLOBALS['config']['DB_USER'],
-        $GLOBALS['config']['DB_PASS'],
-        $GLOBALS['config']['DB_NAME']
-    );
-
-    if ($conn->connect_error) {
-        die("Connection failed: " . $conn->connect_error);
+    try {
+        $conn = Database::getConnection();
+    } catch (\Throwable $e) {
+        error_log('index.php: database connection failed: ' . $e->getMessage());
+        http_response_code(500);
+        die('Sorry, something went wrong. Please try again shortly.');
     }
 
     // Authenticate user via Authelia forward auth
@@ -444,5 +442,5 @@ switch (true) {
 
 // Close database connection if it was opened
 if (isset($conn)) {
-    $conn->close();
+    Database::close();
 }