Adds a per-server tools/list cache in McpRouter (positive + negative TTL)
so a slow or dead upstream only stalls the first discovery call, not every
subsequent client request. Invalidated on upstream add/remove.
Health probes now apply a default liveness spec (tools/list via the real
production path) to any RUNNING instance without an explicit healthCheck,
so synthetic and real failures converge on the same signal.
Includes supporting updates in mcpd-client, discovery, upstream/mcpd,
seeder, and fulldeploy/release scripts.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>