fix: 0 test failures; FileService; real RagService; emergency probe; chat return

fix: @spaces.GPU wrapper for ZeroGPU; 18 real component tests

test: 30 user-story E2E tests (Playwright) + 31 annotated screenshots

feat: mesh graph tab, routing trace, QR invite, remove all fakes, specialized-node tests

feat: BitTorrent-style model weight distribution; no fake LLM in production

feat: impl_ref gaps closed — Nemotron/OpenBMB backends, spec refs, extended UI, HOWTO, multi-node E2E

feat: Phase 2 (M14-M25, X05-X07) + Phase 3 experimental (M26-M31) + E2E tests + docs

feat: implement all M01-M13, X01-X04 modules + quality gate fixes

Build Phase 1 HearthNet Space