Replace the tag/threshold/key/expr CSV body with YAML `vars:` and
`tags:` maps. `parseDeclare` validates the body with an exported Zod
schema and returns the same declaration and modifier shapes the
reactivity engine already consumes.
The breaking rename from `parseDeclareCsv` updates the registry, the
journal re-exports, and the `tttk check` role checks, where R003 now
reports schema errors with their path and R004 warns when a block
declares nothing.