RepoGuardian RHD Conversational v5

RepoGuardian RHD v5 redesigns the product around a chat-first repository intelligence workspace while preserving the existing v4 public deployment, deterministic fallback, MCP, evidence grounding, and human-controlled policy.\n\nHighlights:\n- Home route is now the RHD chat workspace.\n- Light premium visual system replaces the dark/neon dashboard-first shell.\n- Desktop left conversation/repository/tool sidebar and right context panel.\n- Premium bottom composer with repository detection, attachment, repository, voice, model/provider, stop/send controls.\n- New read-only /api/v5 workspace, conversations, capabilities, and architecture endpoints.\n- Deterministic Mermaid/SVG architecture artifacts generated from synchronized repository evidence.\n- Multimodal and voice states are truthful: image understanding requires a configured provider, voice remains optional browser-level UX.\n\nValidation completed:\n- Backend pytest: 74 passed.\n- Frontend lint/typecheck/build: passed, 25 static routes.\n- Frontend Playwright: 51 passed.\n- MCP typecheck and smoke test: passed.\n- Public backend health/readiness/v5 smoke checks: passed.\n- Public homepage desktop/mobile browser checks: passed with zero overflow.