feat: Expand Settings page with sub-pages (version, team, password)

[manojbajaj95]

Summary

Improve the Settings area of the Authsome dashboard by adding structured sub-settings: version info, team management, and password change — instead of the current minimal two-card layout.

Current state

Route: /settings → ui/src/app/(authenticated)/settings/page.tsx

Implementation: Renders SettingsView from authsome-dashboard.tsx, which shows only:

• Account card: email, role, principal ID
• Daemon card: version string, encryption label

// ui/src/components/authsome-dashboard.tsx — SettingsView (~lines 1488–1514)
<SectionHeader description="Local daemon and account context." title="Settings" />
// Two static KeyValue cards — no sub-navigation, no actions

Related but elsewhere:

• Principals / team: /principal (admin-only nav item) — separate from Settings
• Password / account auth: hosted mode uses HostedAccountService + UI session JWT (src/authsome/server/routes/ui.py) — login/register flows exist at /login but no in-app password change
• Version: shown inline in Daemon card; no dedicated about/version page

Proposed work

Restructure Settings as a hub with sub-pages or tabs:

Sub-setting	Content
General / Account	Email, role, principal ID (current Account card)
Version / About	Daemon version, build info, links to docs/changelog
Team management	Invite/manage principals or team members (may consolidate or link to /principal)
Password & security	Change password (hosted accounts), session management

Design considerations

• CONTEXT.md notes authsome is single-tenant — "team" may mean principal membership / identity claims, not multi-org. Align copy and scope with domain model (Principal, IdentityClaimRecord).
• Admin-only sections (team-wide principal management) should respect data.account.isAdmin.
• Match visual patterns from ui/DESIGN.md and consistency work tracked separately.

Relevant files

• ui/src/components/authsome-dashboard.tsx — SettingsView, NAV_ITEMS
• ui/src/app/(authenticated)/settings/page.tsx
• ui/src/lib/authsome-api.ts — dashboard/account API types
• src/authsome/server/routes/ui.py — register, login, logout
• src/authsome/server/hosted_account.py (if exists) — password operations

Acceptance criteria

• Settings has clear sub-navigation (tabs or nested routes under /settings/*).
• Version/about information is accessible in a dedicated sub-section.
• Hosted users can change password from the UI (API + form).
• Team/principal management is reachable from Settings (inline or linked) with correct role gating.