fix: transcode monitor reads STATE_DIR from conf instead of hardcoded /tmp

vv_transcode_sessions() was hardcoded to /tmp/transcode_state.db but master.conf
sets TRANSCODE_STATE_FILE=$STATE_DIR/transcode_state.db which resolves to
/boot/config/plugins/varaverk/State_Files/transcode_state.db. Page always showed
"ramdisk_setup.sh not yet run" despite state file being present and populated.

Plugin/unraid/include/common.php

@@ -726,7 +726,9 @@ function vv_parse_bash_array(string $raw, string $varName): array {
 }
 
 function vv_transcode_sessions(): array {
-    $stateFile = '/tmp/transcode_state.db';
+    $v         = vv_conf_vars();
+    $stateDir  = rtrim($v['STATE_DIR'] ?? '/boot/config/plugins/varaverk/State_Files', '/');
+    $stateFile = $v['TRANSCODE_STATE_FILE'] ?? "$stateDir/transcode_state.db";
     if (!file_exists($stateFile)) return ['available' => false];
 
     $raw = [];