[Story]: Settings hub

[adoLime]

User Story

As a user, I want a single settings page where I can manage my theme preference, edit my profile so that all personal configuration lives in one predictable place and the chat feels transparent instead of frozen.

Context & Motivation

• Type: Functional (UX)
• Parent epic: 12 EPIC - UX, Documentation & Pilot Release #63 (12 EPIC – UX, Documentation & Pilot Release)
• Teams: team:frontend (hub + chat-loading UX), team:backend (only if a chat-status endpoint gap exists)
• Source: User request — "Einstellungen: Light/dark mode, was der user im chat sieht während eine antwort generiert wird, edit user profile, etc."
• Already implemented (just wired into the hub, not rebuilt):
  • Dark/Light mode — ThemeProvider + ThemeToggle + localStorage persist (NFR MP Define dev team split (Backend, Retrieval/AI, Frontend) #3 ✓).
  • Edit user profile — ProfilePage / ProfileLayout + Frontend — profile edit form #208 (closed); story [Story]: Edit user profile #113 (open, Sprint 4).
• New in this story:
  • A central /settings route as the single hub (today: only /profile exists, theme toggle is scattered in the sidebar).
  • Chat loading/generation UX — concrete progress/typing indicator + cancel option while the LLM streams an answer (NFR MP Channels #4 — current gap; no loading/streaming/progress hits in features/chatbot).
• Related: NFR MP Define dev team split (Backend, Retrieval/AI, Frontend) #3 (dark mode) + MP Channels #4 (chat loading state), [Story]: Edit user profile #113 (edit profile — open), [Story]: Local LLM for core chat (with vision support) #95 (local LLM — streaming).
• Sister story: "Dedicated role-management view (PM/Admin) reachable from settings" (02 EPIC - Security, Privacy & Local AI Governance #51) — provides the role-management section reached from this hub.

Acceptance Criteria

• A /settings route exists and is reachable from the main navigation; it groups theme, profile, and chat sections.
• Theme: the existing ThemeToggle has a fixed home in settings (light/dark/system preference) — no behaviour change, just placement.
• Profile: the existing profile-edit form (Frontend — profile edit form #208) is reachable from settings; the separate /profile route may stay or redirect.
• Chat generation UX: while the LLM is generating/streaming an answer, the chat shows a clear progress/typing indicator (icon + text label, not colour alone — per AGENTS.md §7) and a cancel option; empty/error states handled (NFR MP Channels #4).
• All sections are responsive (desktop primary, mobile stacks — AGENTS.md §8) and work in light/dark themes (§7).
• Empty / loading / error states; i18n (en/de).

Sub-Tasks (by team)

• Frontend — /settings route + section layout; wire existing ThemeToggle + profile-edit form; chat-loading/typing indicator + cancel button.
• Backend — (only if needed) expose a lightweight chat-status/streaming endpoint if the current chat API doesn't already support progress signals; otherwise no backend change.
• QA — tests for settings navigation, chat-loading indicator states (generating / streaming / error / cancelled), responsive + light/dark.

Dependencies

• Reuses (no rebuild): Frontend — profile edit form #208 (profile edit form), ThemeProvider / ThemeToggle.
• Related: [Story]: Edit user profile #113 (edit profile story — open, Sprint 4), NFR MP Define dev team split (Backend, Retrieval/AI, Frontend) #3 + MP Channels #4.
• No hard blocker — all building blocks exist; chat-loading UX is the only genuinely new piece.