fix(pipeline): add redis+libretranslate to homelab, make Asynq enqueue errors non-fatal

- homelab/docker-compose.yml: add redis:7-alpine service (port 6379 bound to host
  so Caddy TLS proxy on prod can reach it), add libretranslate service, add
  redis_data and libretranslate_data volumes
- asynqqueue/producer.go: Asynq enqueue failures are now logged as warnings instead
  of returned as errors — PB record already exists so runner picks it up via poll
- backend/main.go: pass logger to NewProducer

Root cause: Redis was not reachable at 192.168.0.109:6379 because the redis
container had no host port binding. Caddy TLS proxy terminates TLS but could
not TCP-connect to the backend Redis.

backend/internal/asynqqueue/producer.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"log/slog"
 
 	"github.com/hibiken/asynq"
 	"github.com/libnovel/backend/internal/taskqueue"
@@ -14,13 +15,15 @@ import (
 type Producer struct {
 	pb     taskqueue.Producer // underlying PocketBase producer
 	client *asynq.Client
+	log    *slog.Logger
 }
 
 // NewProducer wraps an existing PocketBase Producer with Asynq dispatch.
-func NewProducer(pb taskqueue.Producer, redisOpt asynq.RedisConnOpt) *Producer {
+func NewProducer(pb taskqueue.Producer, redisOpt asynq.RedisConnOpt, log *slog.Logger) *Producer {
 	return &Producer{
 		pb:     pb,
 		client: asynq.NewClient(redisOpt),
+		log:    log,
 	}
 }
 
@@ -49,7 +52,9 @@ func (p *Producer) CreateScrapeTask(ctx context.Context, kind, targetURL string,
 	}
 	if err := p.enqueue(ctx, taskType, payload); err != nil {
 		// Non-fatal: PB record exists; runner will pick it up on next poll.
-		return id, fmt.Errorf("asynq enqueue scrape (task still in PB): %w", err)
+		p.log.Warn("asynq enqueue scrape failed (task still in PB, runner will poll)",
+			"task_id", id, "err", err)
+		return id, nil
 	}
 	return id, nil
 }
@@ -68,7 +73,10 @@ func (p *Producer) CreateAudioTask(ctx context.Context, slug string, chapter int
 		Voice:    voice,
 	}
 	if err := p.enqueue(ctx, TypeAudioGenerate, payload); err != nil {
-		return id, fmt.Errorf("asynq enqueue audio (task still in PB): %w", err)
+		// Non-fatal: PB record exists; runner will pick it up on next poll.
+		p.log.Warn("asynq enqueue audio failed (task still in PB, runner will poll)",
+			"task_id", id, "err", err)
+		return id, nil
 	}
 	return id, nil
 }