IA: 3-item navigation + Memories hub (Agents/Rooms/Tags grouping) + agent identity

[ajianaz]

Requires uteke: v0.16.0+ (existing endpoints) · Epic: #289

What

• Navigation collapses to Home · Memories · Documents (+ Settings). Lifecycle → Settings→Maintenance (Settings consolidation + Maintenance (Lifecycle moves here, dry-run preview) #290); Graph → exploration mode inside Memories (read-only until uteke#1180 fix ships); Namespaces → filter chip + topbar switcher (read-only).
• Memories hub: secondary panel grouping Agents | Rooms | Tags; room CRUD lives here (create/rename/delete via ConfirmDialog).
• Agent identity on every memory row: stable per-agent color + name + action verb + relative time (data: author, author_type), per P36 recognition-over-recall; raw UUIDs move to Copy-ID disclosure.

Why

Current nav mirrors uteke's DB schema, not user jobs; 7 equal-weight items cause choice paralysis (P19/P29); writer identity is the #1 trust cue for a read-agents-output tool.

Testing

• Vitest: grouping providers (by agent/room/tag), identity color mapping stability.
• E2E: every destination reachable ≤2 clicks; old views redirect; room CRUD round-trip.
• Visual QA: identity colors consistent across views.