Remove daemon storage cache (bd-33, bd-34, bd-35)

- Deleted server_cache_storage.go (~300 lines)
- Removed cache fields from Server struct
- Simplified database routing to use s.storage directly
- Removed cache metrics from health and metrics endpoints
- Deleted server_eviction_test.go (cache eviction tests)
- Cleaned up limits_test.go (removed cache assertions)
- All tests passing

internal/rpc/server_lifecycle_conn.go

@@ -12,8 +12,6 @@ import (
 	"runtime"
 	"sync/atomic"
 	"time"
-
-	"github.com/steveyegge/beads/internal/storage"
 )
 
 // Start starts the RPC server and listens for connections