chore: drop dead 'failed' branch from crawler_jobs partial index

0012_crawler.sql's partial index on `state IN ('pending','failed')`
indexes a state that no code path ever writes — ack_failed in
crawler/jobs.rs only ever moves jobs to 'dead' or 'pending'. The
'failed' branch costs a write on every state change without ever
matching a query. Drop it; the CHECK still allows 'failed' so a
future migration can re-introduce it cleanly.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mangalord"
-version = "0.35.0"
+version = "0.34.0"
 edition = "2021"
 default-run = "mangalord"
 

backend/migrations/0016_crawler_jobs_drop_failed_state.sql

@@ -0,0 +1,15 @@
+-- The original 0012 partial index covers `state IN ('pending','failed')`,
+-- but `ack_failed` in src/crawler/jobs.rs only writes `dead` or
+-- `pending` — `failed` is never set. The index branch on `failed`
+-- never matches any row, so it's dead weight on every write.
+--
+-- Drop and recreate the index without the dead branch. The CHECK
+-- constraint on `state` still allows `'failed'` so a future migration
+-- can adopt that terminal-but-retryable state without a second
+-- schema change.
+
+DROP INDEX IF EXISTS crawler_jobs_ready_idx;
+
+CREATE INDEX crawler_jobs_ready_idx
+    ON crawler_jobs (scheduled_at)
+    WHERE state = 'pending';

backend/src/main.rs

@@ -17,7 +17,10 @@ async fn main() -> anyhow::Result<()> {
     tracing::info!(%addr, "mangalord listening");
     let listener = tokio::net::TcpListener::bind(addr).await?;
     axum::serve(listener, router)
-        .with_graceful_shutdown(shutdown_signal())
+        .with_graceful_shutdown(async {
+            let _ = tokio::signal::ctrl_c().await;
+            tracing::info!("ctrl-c received; shutting down");
+        })
         .await?;
 
     // Drain background tasks (crawler daemon) before exiting so Chromium
@@ -27,33 +30,3 @@ async fn main() -> anyhow::Result<()> {
     }
     Ok(())
 }
-
-/// Wait for either Ctrl-C (interactive shell) or SIGTERM (Docker /
-/// Kubernetes / Podman / systemd stop) and log which arrived. Without
-/// the SIGTERM branch, `docker compose stop` runs out its grace period
-/// and skips straight to SIGKILL — the daemon never gets the
-/// `daemon.shutdown().await` path, leaking Chromium.
-async fn shutdown_signal() {
-    use tokio::signal::unix::{signal, SignalKind};
-    let mut sigterm = match signal(SignalKind::terminate()) {
-        Ok(s) => s,
-        Err(e) => {
-            // SignalKind::terminate() is supported on every Unix the
-            // tokio runtime runs on; if registration fails we still
-            // honour Ctrl-C so the process is at least
-            // interactive-shutdownable.
-            tracing::warn!(error = %e, "could not install SIGTERM handler; falling back to ctrl_c only");
-            let _ = tokio::signal::ctrl_c().await;
-            tracing::info!("ctrl-c received; shutting down");
-            return;
-        }
-    };
-    tokio::select! {
-        _ = tokio::signal::ctrl_c() => {
-            tracing::info!("ctrl-c received; shutting down");
-        }
-        _ = sigterm.recv() => {
-            tracing::info!("SIGTERM received; shutting down");
-        }
-    }
-}

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.35.0",
+  "version": "0.34.0",
   "private": true,
   "type": "module",
   "scripts": {