chore: bump silo-plugin-sdk to v0.18.0

[Quick104]

The catalog updater decodes each source manifest with the SDK's protobuf types and discards fields it doesn't know. SDK v0.16.1 predates request_router.supports_seasons, so the catalog entry for silo.requests.arr v0.1.6 dropped the flag. Silo stores capability metadata from the catalog entry when it installs or updates a plugin from the catalog, so servers that get v0.1.6 from the catalog would never send it season requests.

This bumps the SDK to v0.18.0, the version the arr plugin is built against. No tooling code changes. After merge, rerunning Update Catalog for Silo-Community/silo-plugins-requests-arr v0.1.6 restores the flag.

Validation

• GOWORK=off go vet ./..., GOWORK=off go test ./... and go run ./cmd/check-catalog pass.
• Running cmd/update-catalog locally for Silo-Community/silo-plugins-requests-arr v0.1.6 adds "request_router": {"supports_seasons": true} to the arr capability and changes nothing else; check-catalog accepts the result.

Related issue: N/A

AI disclosure

• Harness: Claude Code
• Tool(s): Claude Code
• Model(s): claude-opus-5-5 (Claude Opus 5.5, 1M context)
• Involvement: Fully AI-generated. The agent found the dropped flag while confirming the v0.1.6 catalog entry and verified the bump locally.

🤖 Generated with Claude Code