Storage-mode awareness pass + doc update for System_Essentials through Partnership

All state/data file paths in scripts and PHP now resolve via STATE_DIR / DATA_DIR /
PERSISTENT_CONF_CACHE instead of hardcoded /boot/config/ or /tmp/ paths, so the
ecosystem works in both internal and appdata storage modes.

PHP layer (watchdog.php, partnership.php, fallback.php, monitor.php, snapshot.php,
config.php): all state reads switched to STATE_DIR constant; remote state reads use
the new vv_remote_state_cmd() helper which resolves the remote's SCRIPTS_DIR via
their varaverk.cfg before building the path.

conf_sync.sh: fixed SCRIPTS_ROOT → SCRIPTS_DIR bug on MY_CONF path; added
_remote_scripts_dir() to resolve partner's SCRIPTS_DIR before SCP pull.

fallback.php page: added controls card (PARTNERSHIP_ENABLED, FALLBACK_ENABLED,
FALLBACK_RSYNC_ENABLED toggles), status grid, and settings card.

README and Manual updated for System_Essentials, Watchdogs, Fallback, Rsync,
Media, Monitors, Orchestrators, Partnership: added new scripts (conf_sync,
conf_cache_save/restore, conf_cache_watchdog, play_state_sync, start_webhook_listener,
upgrade_webhook_handler), corrected all stale /boot/config/ state file paths to
$STATE_DIR/$DATA_DIR, noted webgui/php_fpm/mover/user_scripts scripts moved to
Plugin/unraid/System_Essentials, fixed start_webhook_listener.sh header (Node.js,
not PHP -S).

Plugin/unraid/include/monitor.php

@@ -58,7 +58,7 @@ function vv_fallback_state(): array {
     $reqStrikes = (int)($vars['FALLBACK_HANDBACK_STRIKES'] ?? 3);
     $suspendAfter = (int)($vars['FALLBACK_PARTNERSHIP_SUSPEND_AFTER'] ?? 120);
 
-    $stateFile = '/tmp/fallback_state.db';
+    $stateFile = STATE_DIR . '/fallback_state.db';
     if (!file_exists($stateFile)) {
         return ['state' => 'UNKNOWN', 'enabled' => $enabled, 'check_interval' => $interval,
                 'handback_strikes' => 0, 'handback_strikes_required' => $reqStrikes,
@@ -164,7 +164,7 @@ function vv_watchdog_summary(): array {
     usort($restarts, fn($a, $b) => $b['ts'] - $a['ts']);
 
     // Reboots (12 h)
-    $rebootRaw = @file_get_contents('/boot/config/system_watchdog_reboots.db') ?: '';
+    $rebootRaw = @file_get_contents(STATE_DIR . '/system_watchdog_reboots.db') ?: '';
     $rbootCutoff = time() - 43200;
     $reboots = 0;
     foreach (explode("\n", trim($rebootRaw)) as $line) {