The old coerce() used regex heuristics to decide whether a value was a
number, boolean, or JSON blob. That turned every stringly-typed field
with numeric content ("1.0", "0.5") into a number and silently stored
the wrong JS type — `colony config set embedding.model 1.0` would
persist the number 1.

Replace it with `coerceForPath(raw, path)` that walks SettingsSchema
down to the target field and coerces based on the leaf zod type. Uses
`_def.typeName` strings instead of `instanceof z.ZodFoo` because the
CLI bundles its own zod copy via tsup and nominal instanceof fails
across bundle boundaries even though the runtime shape matches.