fix(core): throttle volume-ownership sweep to first-seen + hourly per container

The sweep podman-execs into every running container; doing that on each 30s
reconcile tick was a permanent conmon 'Failed to create container' storm on
hosts where exec from the backend's cgroup context fails (Debian 13 first
boot). Ownership drift is an install/OTA-time event — sweep on first pass
after a container appears, then at most hourly.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/archipelago/src/container/prod_orchestrator.rs

@@ -301,6 +301,33 @@ fn unrepairable_ownership() -> &'static std::sync::Mutex<std::collections::HashS
     SET.get_or_init(|| std::sync::Mutex::new(std::collections::HashSet::new()))
 }
 
+/// Per-container timestamp of the last volume-ownership sweep. The sweep's
+/// write-probes are `podman exec`s into EVERY running container; running them
+/// on every 30s reconcile tick meant six-plus cross-context exec attempts per
+/// tick forever — a permanent conmon "Failed to create container" storm on
+/// hosts where exec from the backend's cgroup context fails (Debian 13 first
+/// boot, 2026-07-19). Ownership drift is an install/OTA-time event, not a
+/// steady-state one: sweep each container on the first pass after it appears,
+/// then at most once per hour.
+fn ownership_sweep_due(name: &str) -> bool {
+    const SWEEP_INTERVAL: std::time::Duration = std::time::Duration::from_secs(60 * 60);
+    static LAST: std::sync::OnceLock<
+        std::sync::Mutex<std::collections::HashMap<String, std::time::Instant>>,
+    > = std::sync::OnceLock::new();
+    let map = LAST.get_or_init(|| std::sync::Mutex::new(std::collections::HashMap::new()));
+    let Ok(mut map) = map.lock() else {
+        return true;
+    };
+    let now = std::time::Instant::now();
+    match map.get(name) {
+        Some(last) if now.duration_since(*last) < SWEEP_INTERVAL => false,
+        _ => {
+            map.insert(name.to_string(), now);
+            true
+        }
+    }
+}
+
 /// App-agnostic, userns-mapping-proof volume-ownership repair for a RUNNING
 /// container.
 ///
@@ -1739,6 +1766,11 @@ impl ProdContainerOrchestrator {
                 if crate::app_ops::lifecycle_op_in_flight(&c.name) {
                     continue;
                 }
+                // Throttled: first pass after the container appears, then
+                // hourly — not on every 30s tick (see ownership_sweep_due).
+                if !ownership_sweep_due(&c.name) {
+                    continue;
+                }
                 if ensure_running_container_ownership(&c.name).await {
                     tracing::info!(container = %c.name, "volume ownership repaired during reconcile — restarting to recover");
                     let _ = tokio::process::Command::new("podman")