docs: rebuild README — remote visual style + v2.8 features

Adopts remote README template (badges, linked bullet agents, numbered
quick start). Adds: VoidWeaver specialized node, phi_compute section,
all 4 skills in table, redacted-terminal skill usage guide with
example output, Groq parallel inference docs, Railway persistent
volume note, Option C consolidation results.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: redactedmeme