Initial Meterbox commit with boot disk usage metric.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/cleanup.rs

@@ -0,0 +1,64 @@
+use std::time::Duration;
+
+use crate::AppState;
+
+/// Background job: age retention + hard SQLite size cap (default 10 GiB).
+pub fn spawn(state: AppState) {
+    tokio::spawn(async move {
+        // Run once shortly after boot, then on the configured cadence.
+        tokio::time::sleep(Duration::from_secs(15)).await;
+        run_once(&state);
+
+        let secs = state.config.cleanup_interval_secs.max(60);
+        let mut ticker = tokio::time::interval(Duration::from_secs(secs));
+        ticker.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);
+        // Skip the immediate first tick (already ran above).
+        ticker.tick().await;
+
+        loop {
+            ticker.tick().await;
+            run_once(&state);
+        }
+    });
+}
+
+fn run_once(state: &AppState) {
+    let max = state.config.max_db_bytes;
+    // Aim for 90% of the cap so we don't thrash at the ceiling.
+    let target = (max as f64 * 0.90) as u64;
+    match state
+        .db
+        .run_cleanup(state.config.retention_days, max, target)
+    {
+        Ok(report) => {
+            tracing::info!(
+                deleted_by_age = report.deleted_by_age,
+                deleted_by_size = report.deleted_by_size,
+                vacuumed = report.vacuumed,
+                bytes_before = report.bytes_before,
+                bytes_after = report.bytes_after,
+                rows = report.rows_after,
+                max_bytes = max,
+                "sqlite cleanup finished"
+            );
+        }
+        Err(e) => tracing::warn!(error = %e, "sqlite cleanup failed"),
+    }
+
+    match state.db.get_settings() {
+        Ok(settings) if settings.cleanup_logs_older_than_3_months => {
+            match state
+                .db
+                .prune_health_results_older_than(crate::settings::HEALTH_LOG_RETENTION_DAYS)
+            {
+                Ok(n) if n > 0 => {
+                    tracing::info!(deleted = n, "pruned health logs older than 3 months")
+                }
+                Ok(_) => {}
+                Err(e) => tracing::warn!(error = %e, "health log prune failed"),
+            }
+        }
+        Ok(_) => {}
+        Err(e) => tracing::warn!(error = %e, "load settings for cleanup failed"),
+    }
+}