verdant-runtime — live cache runtime that the M1 MCP server consumes.
Build sequence so far: step 2 lands the content-addressed object
store (store); step 3 lands the LiveCache surface that wraps the
store with a registry, file-root revalidation, and dirty invalidation
(cache). Step 4 (file revalidation path) is folded into the cache
module; step 5 wires LiveCache into the verdant-mcp read tool.