feat: comprehensive audit + Tier 3 wiring (security/correctness/features)

Multi-agent audit + fix pass covering bugs, security, dead config wiring,
and missing features. All quality gates green: build/vet/test -race/govulncheck/
golangci-lint. Frontend tests 47/47.

SECURITY & CORRECTNESS

- Scanner pipeline fail-closed: cache.go scan timeout now 503 (was goto servePkg);
  scanner.go all-scanners-fail saves ScanStatusError; CheckVulnerabilities blocks
  on missing/error result instead of allowing.
- Scanner argv corrections: govulncheck source-mode + go.mod discovery;
  npm-audit generates lockfile via npm install --package-lock-only --ignore-scripts;
  pip-audit per-extension dispatch (wheel direct / sdist extract+pyproject).
- GHSA version-range filtering implemented (was always-include); url.QueryEscape
  on package name.
- pypi SSRF closed via host allowlist on original_url; url.QueryEscape on
  rewriteURL output.
- Path traversal: cache temp file uses os.CreateTemp; smb keyToPath sanitized;
  filesystem keyToPath returns error + filepath.Abs prefix-verify.
- Goroutine leaks plugged: cache.cleanupWorker stop channel; auth.ValidationCache
  Stop() with sync.Once; ws.unregister buffered with non-blocking send.
- WebSocket double-close panic fixed via sync.Once Client.closeSend().
- Race conditions: gormstore.registryCache sync.RWMutex (was concurrent map
  panic); auth.LastUsedAt no longer mutated under RLock; analytics strict
  lock-ordering invariant (statsMu before downloadsMu).
- Auth validator fails CLOSED on transport/unknown-status errors (was returning
  true,err 'allow cache fallback').
- Credential cache hash full SHA256 (was 8-byte truncate; eliminates 2^32
  collision risk).
- filesystem.fs.used incremented after successful rename (no quota inflation
  race).
- gormstore aggregation events deleted in same tx as insert (no double-counting).
- gormstore.SavePackage uses Updates(map) so zero-value security flags
  (RequiresAuth=false) can be cleared.
- partition_manager validates partition name regex before DROP TABLE.
- vcs/git: version regex validation rejects --option-injection; checkout uses
  --detach -- separator; removed TrimPrefix(repo,'v') that corrupted vault/
  vitess/vim-go.
- WebSocket CheckOrigin allowlist (was return true; CSWSH closed); same-origin
  default + ServerConfig.AllowedOrigins.
- fiber CVE GO-2026-4543 patched (v2.52.10 -> v2.52.12).

FUNCTIONAL FEATURES

- API key DB persistence: APIKeyModel + migration 202604280002, full CRUD,
  async LastUsedAt updates with WaitGroup-tracked goroutines drained on Close.
- Admin bootstrap via GOHOARDER_BOOTSTRAP_ADMIN_KEY env var; idempotent
  (skipped when non-revoked admin already exists).
- Auth middleware factory in pkg/app: RequireAuth, RequireRole, RequirePermission,
  OptionalAuth. Mounted on proxy + read APIs when Auth.Enabled=true.
  DELETE /api/packages/* requires admin role. /health public for k8s probes.
- NFS storage backend: pkg/storage/nfs wraps filesystem with /proc/mounts
  detection (Linux), post-write fsync, read-after-write health probe.
- WebSocket real-time pipeline: pkg/events Broadcaster interface; cache + scanner
  managers emit EventPackageCached / EventPackageDownloaded / EventScanComplete;
  app.go runs 30s EventStatsUpdate ticker. Frontend has full WS client (reconnect
  with exponential backoff 1s->30s, 25s heartbeat, subscriber pattern), Pinia
  realtime store, Dashboard live indicator + activity feed + reactive stats
  override.
- TLS termination: fiber.ListenTLS when Server.TLS.Enabled.
- Pre-warming: Prewarming.Enabled flag wired (was hardcoded false); Interval,
  MaxConcurrent, TopPackages plumbed.
- NetworkConfig wired (timeouts, retry, rate-limit, circuit-breaker).
- AuthConfig.BcryptCost wired.
- Security.Scanners.Static.MaxPackageSize plumbed to cache.io.LimitReader.
- Handlers.{Go,NPM,PyPI}.Enabled gates route mounting.
- Graceful shutdown: authManager.Close drains async writes.

LINT/HYGIENE

- 80 golangci-lint issues resolved: errcheck (Close/Write/RemoveAll wrapped),
  gofmt, gosec G104/G306, govet shadow renames + fieldalignment reorders,
  staticcheck ST1000 pkg comments + QF1003 tagged switches + QF1008 embedded
  field selectors + QF1001 De Morgan's law.

BEHAVIOR CHANGES

- Scanner now fail-closed: deployments without scanner binaries
  (trivy/govulncheck/npm-audit/pip-audit/grype) BLOCK packages instead of
  serving unscanned. Add binaries or plan a future allow-on-scan-error flag.
- WS origin defaults to same-origin; cross-origin dashboards must set
  server.allowed_origins.
- Validator no longer fails open; private packages won't serve from cache when
  validation can't be performed.
- download_events retention dropped from 24h to ~5min (deleted in agg tx).
  Migration 202604280001 purges pre-upgrade events.
- DELETE /api/packages/* requires admin role when auth enabled.

NEW PACKAGES

- pkg/events  - Broadcaster interface
- pkg/storage/nfs  - NFS-aware filesystem wrapper

DEFERRED (out of scope this pass)

- Static scanner implementation (config defines AllowedLicenses/MaxPackageSize/
  BlockSuspicious but pkg/scanner/static/ does not exist).
- AuthConfig.AuditLog wiring (no audit log infra yet).
- CacheConfig.TTLOverrides passthrough (would touch cache.Config beyond
  integrator scope).

pkg/metadata/interface.go

@@ -1,11 +1,19 @@
+// Package metadata defines the Store interface and shared model types for
+// package metadata persistence backends.
 package metadata
 
 import (
 	"context"
+	"errors"
 	"strings"
 	"time"
 )
 
+// ErrNotImplemented signals that an optional MetadataStore method is not
+// supported by the current backend (e.g. a backend may not persist API keys).
+// Callers should treat it as a non-fatal capability check.
+var ErrNotImplemented = errors.New("metadata: operation not implemented by this backend")
+
 // Store is an alias for MetadataStore for convenience
 type Store = MetadataStore
 
@@ -62,10 +70,48 @@ type MetadataStore interface {
 	// AggregateDownloadData aggregates raw download events and cleans up old data
 	AggregateDownloadData(ctx context.Context) error
 
+	// SaveAPIKey persists (insert or update) an API key record. Backends that
+	// do not implement persistent API keys MUST return ErrNotImplemented.
+	SaveAPIKey(ctx context.Context, key *APIKey) error
+
+	// GetAPIKey retrieves a single API key by ID. Returns ErrNotImplemented if
+	// the backend does not persist API keys. Returns a not-found error wrapped
+	// from the backend if the key does not exist.
+	GetAPIKey(ctx context.Context, id string) (*APIKey, error)
+
+	// ListAPIKeys returns all API keys (including revoked) so callers can
+	// decide whether to filter. Returns ErrNotImplemented for backends that
+	// do not persist API keys.
+	ListAPIKeys(ctx context.Context) ([]*APIKey, error)
+
+	// DeleteAPIKey removes an API key by ID. Returns ErrNotImplemented for
+	// backends that do not persist API keys.
+	DeleteAPIKey(ctx context.Context, id string) error
+
+	// UpdateAPIKeyLastUsed updates the last-used timestamp without rewriting
+	// the rest of the row. Implementations should make this cheap; auth.Manager
+	// may invoke it asynchronously on every successful validation.
+	UpdateAPIKeyLastUsed(ctx context.Context, id string, t time.Time) error
+
 	// Close closes the metadata store
 	Close() error
 }
 
+// APIKey is the storage-layer representation of an authentication API key.
+// It is intentionally separate from auth.APIKey to avoid an import cycle:
+// the auth package depends on metadata, never the other way around.
+type APIKey struct {
+	CreatedAt   time.Time  `json:"created_at"`
+	ExpiresAt   *time.Time `json:"expires_at,omitempty"`
+	LastUsedAt  *time.Time `json:"last_used_at,omitempty"`
+	ID          string     `json:"id"`
+	KeyHash     string     `json:"key_hash"`
+	Project     string     `json:"project"`
+	Role        string     `json:"role"`
+	Permissions string     `json:"permissions,omitempty"` // JSON-encoded list (optional)
+	Revoked     bool       `json:"revoked"`
+}
+
 // Package represents package metadata
 type Package struct {
 	CachedAt        time.Time         `json:"cached_at"`