discogs-mcp v3.5.0 — Egress relay, faster 429 recovery

This release is about the Discogs rate limit: fewer 429s to begin with, and a quick, clear answer when one does happen. Discogs throttles by source IP and a Worker's calls leave from Cloudflare's shared IPs, so discogs-mcp can now send its traffic through a relay on a machine you own (the hosted instance already does). When you are throttled, an interactive call tells you within seconds. What's new Route Discogs calls through your own IP. Point DISCOGS_RELAY_ORIGIN at a Cloudflare Tunnel to any always-on machine (a home Mac, a small VPS) running a local reverse proxy in front of api.discogs.com, guard it with a Cloudflare Access service token, and the whole 60-requests-a-minute budget is yours. The README has the setup, including the X-Forwarded-Host gotcha that bites cloudflared on its own. If the relay machine is off, calls go direct and nothing stops working. ping and server_info now say how Discogs traffic is leaving ("Discogs egress: via relay relay.discogs-mcp.com, no fallbacks…