Merge pull request #32 from cryptopoly/feature/chat-level-up

[cryptopoly]

Brings the chat / image / video phase 2-3 work into staging on top of the recent Windows runtime fixes. Conflict resolution notes:

• gpu.py / test_gpu_detection.py: kept staging's subprocess-based torch probe (fixes a Windows DLL lock that PR 32's in-process import would re-introduce). Ported PR 32's torch_install_warning() in alongside it so image_runtime / video_runtime imports keep working.
• setup.py: kept staging's reset_torch_status_cache + reset_vram_total_cache (superset of PR 32's reset).
• pyproject.toml: bumped version to 0.7.4.
• VideoStudioTab.tsx: combined PR 32's CPU-fallback danger badge with staging's stricter restart-required condition; dropped staging's duplicate LTX-2 distilled callout (PR 32 has it elsewhere).
• styles.css: kept both library-row-actions layout properties; kept staging's contain: layout on install-log-panel.
• videos.ts: kept staging's estimateVideoRequestPeakGb + nf4RuntimeFootprintForRepo helpers; widened useNf4 type to boolean | null per PR 32; extended NF4 lookup to cover Wan 2.2-T2V-A14B and LTX-Video; PR 32's relaxed risk thresholds (0.85/0.95) carried through. Tests aligned with PR 32's relationship-style assertions.