add missing comments for all components

src/app/eiffel/parser.go

src/app/eiffel/parser_test.go

src/app/eiffel/web.go

src/app/home/web.go

src/app/template/parser/parser.go

src/app/template/service.go

src/app/template/template.go

src/app/template/web/service.go

src/app/template/web/web.go

src/app/user/user_service.go

src/app/user/user_session.go

src/app/user/web/web.go

src/cmd/web/main.go

src/core/config/config.go

src/core/core.go

src/core/event/event.go

src/core/event/event_test.go

src/core/hctx/hctx.go

src/core/herr/herr.go

src/core/persistence/db.go