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/tenant/app/cache_support_test.go

@@ -0,0 +1,50 @@
+package app
+
+import (
+	"context"
+	"errors"
+	"testing"
+	"time"
+
+	sharedcache "github.com/geo-platform/tenant-api/internal/shared/cache"
+)
+
+func TestArticleCacheVersionSeparatesLateWritesAfterInvalidation(t *testing.T) {
+	t.Parallel()
+
+	ctx := context.Background()
+	c := sharedcache.New("memory", nil, sharedcache.WithNamespace("test"))
+	tenantID := int64(42)
+	articleID := int64(7)
+	params := ArticleListParams{Page: 1, PageSize: 10}
+
+	oldVersion := articleCacheVersion(ctx, c, tenantID)
+	oldListKey := articleListCacheKey(tenantID, oldVersion, params)
+	oldDetailKey := articleDetailCacheKey(tenantID, articleID, oldVersion)
+	if err := c.Set(ctx, oldListKey, []byte("generating-list"), time.Minute); err != nil {
+		t.Fatalf("set old list cache: %v", err)
+	}
+	if err := c.Set(ctx, oldDetailKey, []byte("generating-detail"), time.Minute); err != nil {
+		t.Fatalf("set old detail cache: %v", err)
+	}
+
+	invalidateArticleCaches(ctx, c, tenantID, &articleID)
+	newVersion := articleCacheVersion(ctx, c, tenantID)
+	if newVersion == oldVersion {
+		t.Fatalf("expected article cache version to change, stayed %q", newVersion)
+	}
+
+	if err := c.Set(ctx, oldListKey, []byte("late-generating-list"), time.Minute); err != nil {
+		t.Fatalf("late set old list cache: %v", err)
+	}
+	if err := c.Set(ctx, oldDetailKey, []byte("late-generating-detail"), time.Minute); err != nil {
+		t.Fatalf("late set old detail cache: %v", err)
+	}
+
+	if _, err := c.Get(ctx, articleListCacheKey(tenantID, newVersion, params)); !errors.Is(err, sharedcache.ErrNotFound) {
+		t.Fatalf("expected new list key to miss stale late write, got err %v", err)
+	}
+	if _, err := c.Get(ctx, articleDetailCacheKey(tenantID, articleID, newVersion)); !errors.Is(err, sharedcache.ErrNotFound) {
+		t.Fatalf("expected new detail key to miss stale late write, got err %v", err)
+	}
+}