Frontend redesign documentation

[vredchenko]

Summary

• Add ADR-0017 recording the monorepo restructure decision for smartem-frontend
• Publish the frontend design specification (shell chrome, routes, UX principles, state management) refined from working design documents
• Commit the functional requirements spec with updated route paths (session-anchored nesting), spatial context strip replacing breadcrumbs, and corrected stub paths
• Rewrite claude-code/smartem-frontend/REPO-GUIDELINES.md for the npm workspaces monorepo layout (workspace-aware commands, corrected tech stack, both app route tables)
• Update decisions.md index with ADR-0017

Context

Companion to smartem-frontend PR #52 (monorepo restructure). This PR brings devtools documentation in line with the new repository structure and captures design decisions made during the frontend redesign sessions.

Test plan

• ADR-0017 follows the established template (matches ADR-0015 style)
• Design spec reads as a coherent, professional document — no personal names, no internal references, no working-note language
• Requirements spec has updated paths and notes where routes are being redesigned
• REPO-GUIDELINES.md matches the actual monorepo structure and commands
• decisions.md lists ADR-0017