Strip comments from backend and frontend source

Remove Go doc comments, TS/Svelte scaffold comments and explanatory
notes left over from the initial scaffold, plus a few leftover Spanish
notes in the compose file, SQL scripts and env template. Also drops
frontend/src/lib/index.ts, which only held the SvelteKit placeholder
comment and was never imported.

backend/migrations/000001_init.up.sql

@@ -37,5 +37,4 @@ CREATE INDEX idx_services_host_id ON services(host_id);
 CREATE INDEX idx_audit_log_created_at ON audit_log(created_at DESC);
 CREATE INDEX idx_audit_log_user_sub ON audit_log(user_sub);
 
--- Host único de la Fase 1: el mismo servidor donde corre el backend.
 INSERT INTO hosts (name, connection_type) VALUES ('local', 'local');