Language Server - Superwire

The language server should help authors catch workflow issues before execution.

Core features

parse diagnostics with source spans
validation diagnostics for references and schemas
completion for declaration names and root namespaces
hover information for schema fields and agent outputs
go-to-definition for references

Useful completions

input.
secrets.
agent.
schema.
tool.
resource.
prompt.
dynamic.

The LSP should follow the same semantics as executor validation so editor feedback matches runtime behavior.