feat(cache,worker): overhaul cache layer and add generation task lease recovery

- shared/cache: add Options/L1/async/metrics/prefix decorators, multi-key ops, Redis pool tuning, and JSON readthrough metrics
- worker-generate: claim tasks via DB lease + heartbeat, requeue stale queued tasks, expire dead leases with refund/cache invalidation
- tenant: version article cache keys so worker recovery invalidations propagate cleanly
- shared/config: expand Redis (pool/timeouts/TLS) and Generation (lease/recovery) configs with defaults

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

server/internal/worker/generate/article_generation_recovery_test.go

@@ -0,0 +1,72 @@
+package generate
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/geo-platform/tenant-api/internal/shared/config"
+)
+
+func TestNormalizeGenerationTaskRecoveryConfigUsesGenerationDefaults(t *testing.T) {
+	cfg := normalizeGenerationTaskRecoveryConfig(config.GenerationConfig{
+		ArticleTimeout: 90 * time.Second,
+	})
+
+	if cfg.LeaseTTL != 3*time.Minute+30*time.Second {
+		t.Fatalf("expected lease ttl article_timeout+2m, got %s", cfg.LeaseTTL)
+	}
+	if cfg.RecoveryInterval != time.Minute {
+		t.Fatalf("expected recovery interval 1m, got %s", cfg.RecoveryInterval)
+	}
+	if cfg.RecoveryTimeout != 30*time.Second {
+		t.Fatalf("expected recovery timeout 30s, got %s", cfg.RecoveryTimeout)
+	}
+	if cfg.BatchSize != 100 {
+		t.Fatalf("expected batch size 100, got %d", cfg.BatchSize)
+	}
+	if cfg.QueuedStaleAfter != 2*time.Minute {
+		t.Fatalf("expected queued stale after 2m, got %s", cfg.QueuedStaleAfter)
+	}
+	if cfg.MaxAttempts != 3 {
+		t.Fatalf("expected max attempts 3, got %d", cfg.MaxAttempts)
+	}
+}
+
+func TestNormalizeGenerationTaskRecoveryConfigKeepsOverrides(t *testing.T) {
+	cfg := normalizeGenerationTaskRecoveryConfig(config.GenerationConfig{
+		ArticleTimeout:        5 * time.Minute,
+		TaskLeaseTTL:          7 * time.Minute,
+		TaskRecoveryInterval:  15 * time.Second,
+		TaskRecoveryTimeout:   10 * time.Second,
+		TaskRecoveryBatchSize: 12,
+		TaskQueuedStaleAfter:  45 * time.Second,
+		TaskMaxAttempts:       5,
+	})
+
+	if cfg.LeaseTTL != 7*time.Minute ||
+		cfg.RecoveryInterval != 15*time.Second ||
+		cfg.RecoveryTimeout != 10*time.Second ||
+		cfg.BatchSize != 12 ||
+		cfg.QueuedStaleAfter != 45*time.Second ||
+		cfg.MaxAttempts != 5 {
+		t.Fatalf("unexpected recovery config: %#v", cfg)
+	}
+}
+
+func TestGenerationWorkerOwnerIsBounded(t *testing.T) {
+	owner := generationWorkerOwner(strings.Repeat("x", 256))
+	if len(owner) > 128 {
+		t.Fatalf("expected owner to be bounded to 128 chars, got %d", len(owner))
+	}
+	if owner == "" {
+		t.Fatalf("expected non-empty owner")
+	}
+}
+
+func TestGenerationTaskRecoveryFailureMessage(t *testing.T) {
+	message := formatGenerationTaskRecoveryFailure()
+	if !strings.Contains(message, "worker_recovery") {
+		t.Fatalf("expected recovery marker in failure message, got %q", message)
+	}
+}