Fix dead/incorrect vars and consolidate duplicated logic into common.sh

Codebase-wide audit pass: fixed real bugs (SSH hangs missing BatchMode,
local-outside-function no-ops, variable name collisions, a truncated
ratio calc, wrong state-dir path, DARK vs NO_INTERNET drift, and more),
then pulled logic that was duplicated across multiple scripts — arr
cleanup safety gates, docker restart ordering, container maintenance
stop/restart, watchdog state-file helpers, partnership role resolution,
cert expiry checks, remote node discovery, and TMDB discovery scoring —
into common.sh so each now has a single implementation.

Kernel/decision_engine.sh

@@ -65,6 +65,7 @@ score_candidate() {
     local popularity_score="${2:-0}"
     local recency_score="${3:-0}"
     local quality_score="${4:-0}"
+    local TOTAL_SCORE
 
     TOTAL_SCORE=$(( \
         user_score + \