feat(v3): add Dozzle/Uptime Kuma/Gotify; fix Meilisearch catalogue re-index churn

- docker-compose: add dozzle, uptime-kuma, gotify services with Caddy subdomains
  (logs/uptime/push.libnovel.cc); bind-mount dozzle/users.yml for simple auth
- Caddyfile: add site blocks for logs, uptime, push subdomains
- admin layout: add Logs, Uptime, Push tabs to external tools pill
- CatalogueEntry: add Slug field; populated by novelfire scraper
- meili.Client: add BookExists() to check if a book is already indexed
- catalogue_refresh: skip books already present in Meilisearch to prevent
  redundant re-scraping and re-indexing on every runner restart
- docker-compose runner: set RUNNER_SKIP_INITIAL_CATALOGUE_REFRESH=true

v3/backend/internal/runner/catalogue_refresh.go

@@ -51,6 +51,14 @@ func (r *Runner) runCatalogueRefresh(ctx context.Context) {
 			break
 		}
 
+		// Skip books already present in Meilisearch — they were indexed on a
+		// previous run. Re-indexing only happens when a scrape task is
+		// explicitly enqueued (e.g. via the admin UI or API).
+		if r.deps.SearchIndex.BookExists(ctx, entry.Slug) {
+			skipped++
+			continue
+		}
+
 		// Random jitter between books to avoid rate-limiting.
 		jitter := time.Duration(1000+rand.Intn(2000)) * time.Millisecond
 		select {