docs(v1): rewrite team deck around outcomes, not internals

Reframe the presentation on what labdev delivers to each role (PO, designer, full-stack) rather than the architecture/layers. New arc: init → everything is sourced → two AI sessions ship a feature end-to-end → it builds & runs. Sober, restrained theme (single indigo accent, dark section/role slides) instead of the previous loud version. Presenter notes include a copy-paste init block for the live demo.