fix: add self-healing for cache session index inconsistencies

- Auto-repair when session exists in cache but missing from index
- Clean up index when session doesn't exist in cache
- Prevents inconsistent state between session data and index

Author: CodeWithKyrian

src/Session/CacheSessionHandler.php

@@ -27,10 +27,20 @@ public function __construct(
     public function read(string $sessionId): string|false
     {
         $session = $this->cache->get($sessionId, false);
-        if ($session === false || !isset($this->sessionIndex[$sessionId])) {
+        if ($session === false) {
+            if (isset($this->sessionIndex[$sessionId])) {
+                unset($this->sessionIndex[$sessionId]);
+                $this->cache->set(self::SESSION_INDEX_KEY, $this->sessionIndex);
+            }
             return false;
         }
 
+        if (!isset($this->sessionIndex[$sessionId])) {
+            $this->sessionIndex[$sessionId] = $this->clock->now()->getTimestamp();
+            $this->cache->set(self::SESSION_INDEX_KEY, $this->sessionIndex);
+            return $session;
+        }
+
         if ($this->clock->now()->getTimestamp() - $this->sessionIndex[$sessionId] > $this->ttl) {
             $this->cache->delete($sessionId);
             return false;