Improve streaming markdown rendering

Reapply "Render streaming markdown block by block (kills the mid-stream snap)"

Revert "Render streaming markdown block by block (kills the mid-stream snap)"

Render streaming markdown block by block (kills the mid-stream snap)

NVIDIA NIM LLM backend, vg reward model + round-robin/UCB selection, UI fixes

Restore warm Claude Desktop palette (was reverted to teal/blue)

Add admin-token auth, security/streaming tests, DB design doc

Initial commit — APE Modulor for HF Spaces deploy