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/shared/cache/options.go

@@ -0,0 +1,159 @@
+package cache
+
+import (
+	"context"
+	"strings"
+	"time"
+)
+
+const (
+	defaultNamespace        = "geo"
+	defaultCacheJitterRatio = 0.1
+	defaultDeleteScanCount  = int64(500)
+	defaultAsyncFillWorkers = 2
+	defaultAsyncFillBuffer  = 1024
+	defaultAsyncFillTimeout = 2 * time.Second
+	defaultL1TTL            = 30 * time.Second
+)
+
+type Options struct {
+	Namespace        string
+	JitterRatio      float64
+	MetricsEnabled   bool
+	AsyncFillEnabled bool
+	AsyncFillWorkers int
+	AsyncFillBuffer  int
+	AsyncFillTimeout time.Duration
+	L1Enabled        bool
+	L1TTL            time.Duration
+	DeleteScanCount  int64
+}
+
+func DefaultOptions() Options {
+	return Options{
+		Namespace:        defaultNamespace,
+		JitterRatio:      defaultCacheJitterRatio,
+		MetricsEnabled:   true,
+		AsyncFillWorkers: defaultAsyncFillWorkers,
+		AsyncFillBuffer:  defaultAsyncFillBuffer,
+		AsyncFillTimeout: defaultAsyncFillTimeout,
+		L1TTL:            defaultL1TTL,
+		DeleteScanCount:  defaultDeleteScanCount,
+	}
+}
+
+type Option func(*Options)
+
+func WithNamespace(namespace string) Option {
+	return func(o *Options) {
+		o.Namespace = namespace
+	}
+}
+
+func WithJitterRatio(ratio float64) Option {
+	return func(o *Options) {
+		o.JitterRatio = ratio
+	}
+}
+
+func WithMetrics(enabled bool) Option {
+	return func(o *Options) {
+		o.MetricsEnabled = enabled
+	}
+}
+
+func WithAsyncFill(enabled bool, workers, buffer int, timeout time.Duration) Option {
+	return func(o *Options) {
+		o.AsyncFillEnabled = enabled
+		o.AsyncFillWorkers = workers
+		o.AsyncFillBuffer = buffer
+		o.AsyncFillTimeout = timeout
+	}
+}
+
+func WithL1(enabled bool, ttl time.Duration) Option {
+	return func(o *Options) {
+		o.L1Enabled = enabled
+		o.L1TTL = ttl
+	}
+}
+
+func WithDeleteScanCount(count int64) Option {
+	return func(o *Options) {
+		o.DeleteScanCount = count
+	}
+}
+
+func normalizeOptions(options Options) Options {
+	options.Namespace = strings.TrimSpace(options.Namespace)
+	if options.Namespace == "" {
+		options.Namespace = defaultNamespace
+	}
+	if options.JitterRatio < 0 {
+		options.JitterRatio = 0
+	}
+	if options.JitterRatio > 1 {
+		options.JitterRatio = 1
+	}
+	if options.AsyncFillWorkers <= 0 {
+		options.AsyncFillWorkers = defaultAsyncFillWorkers
+	}
+	if options.AsyncFillBuffer <= 0 {
+		options.AsyncFillBuffer = defaultAsyncFillBuffer
+	}
+	if options.AsyncFillTimeout <= 0 {
+		options.AsyncFillTimeout = defaultAsyncFillTimeout
+	}
+	if options.L1TTL <= 0 {
+		options.L1TTL = defaultL1TTL
+	}
+	if options.DeleteScanCount <= 0 {
+		options.DeleteScanCount = defaultDeleteScanCount
+	}
+	return options
+}
+
+type optionsProvider interface {
+	CacheOptions() Options
+}
+
+type optionsCache struct {
+	inner   Cache
+	options Options
+}
+
+func newOptionsCache(inner Cache, options Options) Cache {
+	return &optionsCache{inner: inner, options: normalizeOptions(options)}
+}
+
+func (c *optionsCache) CacheOptions() Options {
+	return c.options
+}
+
+func (c *optionsCache) Get(ctx context.Context, key string) ([]byte, error) {
+	return c.inner.Get(ctx, key)
+}
+
+func (c *optionsCache) GetMulti(ctx context.Context, keys []string) (map[string][]byte, error) {
+	return c.inner.GetMulti(ctx, keys)
+}
+
+func (c *optionsCache) Set(ctx context.Context, key string, value []byte, ttl time.Duration) error {
+	return c.inner.Set(ctx, key, value, ttl)
+}
+
+func (c *optionsCache) SetMulti(ctx context.Context, items []Item) error {
+	return c.inner.SetMulti(ctx, items)
+}
+
+func (c *optionsCache) Delete(ctx context.Context, key string) error {
+	return c.inner.Delete(ctx, key)
+}
+
+func (c *optionsCache) DeleteMany(ctx context.Context, keys []string) error {
+	return c.inner.DeleteMany(ctx, keys)
+}
+
+func (c *optionsCache) DeletePrefix(ctx context.Context, prefix string) error {
+	return c.inner.DeletePrefix(ctx, prefix)
+}