Auto-prune skip-list/intentional-stop entries for uninstalled containers

Neither remove_from_skip_list() nor clear_intentional_stop() can ever
fire for a container that's been fully uninstalled — both only trigger
on seeing it running again. Confirmed live 2026-07-19: Healarr sat on
the skip list nagging "manual intervention needed" every single cycle
for weeks after being removed. Now checks docker inspect for each
entry every cycle and drops it automatically if the container no
longer exists at all.

Watchdogs/docker_watchdog.sh

@@ -676,6 +676,26 @@ CYCLE_START=$(date +%s)
     done
 
     # ── Skip list and intentional stops visibility ───────────────────────────────────────────
+    # Prune entries for containers that no longer exist at all (uninstalled/removed) from both
+    # state files. Neither remove_from_skip_list() nor clear_intentional_stop() can ever fire
+    # for one of these — both only trigger when a container is "seen running again," which never
+    # happens for something that's been uninstalled — so without this an entry nags every cycle
+    # forever (confirmed live 2026-07-19: Healarr, uninstalled weeks earlier, still flagged every
+    # run). Snapshot into an array first — sed -i rewriting the same file a `while read < file`
+    # loop is still iterating is the classic gotcha this avoids.
+    for _prune_file in "$DOCKER_WATCHDOG_FAILED_FILE" "$DOCKER_WATCHDOG_INTENTIONAL_FILE"; do
+        [[ -s "$_prune_file" ]] || continue
+        mapfile -t _prune_snapshot < "$_prune_file"
+        for _prune_container in "${_prune_snapshot[@]}"; do
+            [[ -z "$_prune_container" ]] && continue
+            if ! timeout "$DOCKER_TIMEOUT" docker inspect "$_prune_container" &>/dev/null; then
+                sed -i "/^${_prune_container}$/d" "$_prune_file" 2>/dev/null
+                warn "$_prune_container no longer exists — removed from $(basename "$_prune_file")"
+            fi
+        done
+    done
+    unset _prune_file _prune_snapshot _prune_container
+
     _skip_contents=$(cat "$DOCKER_WATCHDOG_FAILED_FILE" 2>/dev/null | tr '\n' ' ' | xargs)
     [[ -n "$_skip_contents" ]] && warn "$ICON_SKIP Skip list active: $_skip_contents — manual intervention needed"
     _intentional_contents=$(cat "$DOCKER_WATCHDOG_INTENTIONAL_FILE" 2>/dev/null | tr '\n' ' ' | xargs)