When ?stream=true or Accept: text/event-stream, setupSSE opens an
event-stream response; emitted events push as type='event', client
effects as type='effect', and the complete OrbitalEventResponse as
type='complete'. Non-stream path (no query param) returns existing JSON
unchanged. processOrbitalEvent is synchronous so this is buffer-then-
flush; true incremental push is flagged for B3 kernel work.

Adds @almadar/server@^2.14.2 as a prod dep (SSE helpers); externals
@almadar/server in tsup so browser bundles stay clean. SSE helpers
are loaded via dynamic import() inside the async route handler to
avoid bundling the ESM-only package.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>