Replace broken low-level HTTP request flow (req.reader() doesn't exist in zig 0.15) with client.fetch() + Io.Writer.Allocating — same proven pattern as xrpc/transport.zig. Move HTTP client outside pagination loop. Also adds connected_inbound metric and removes per-host rate limiter. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>