fix: use STATE_DIR directly — TRANSCODE_STATE_FILE contains unexpanded bash var

vv_conf_vars() reads conf as text; TRANSCODE_STATE_FILE=$STATE_DIR/... is
returned as a literal string, not expanded. Build path from STATE_DIR directly.

Plugin/unraid/include/common.php

@@ -728,7 +728,7 @@ function vv_parse_bash_array(string $raw, string $varName): array {
 function vv_transcode_sessions(): array {
     $v         = vv_conf_vars();
     $stateDir  = rtrim($v['STATE_DIR'] ?? '/boot/config/plugins/varaverk/State_Files', '/');
-    $stateFile = $v['TRANSCODE_STATE_FILE'] ?? "$stateDir/transcode_state.db";
+    $stateFile = "$stateDir/transcode_state.db";
     if (!file_exists($stateFile)) return ['available' => false];
 
     $raw = [];