feat: extract admin account management rework from PR 124 (#138)

* feat: reorganize admin panel around accounts

* feat: expand admin customer account controls

* feat: add admin account detail management

* fix: remove unused admin account icon import

* refactor: design critique fixes for account pages

- Admin accounts: replace dense card grid with compact DataTable
- Account settings: remove redundant hero card, stat grid, header pills
- Fix bg-accent (orange) misuse on decorative elements across 7 files
- Add ConfirmButton for destructive actions (deactivate, remove member)
- Replace single-field modals with inline editing (plan, trial)
- Add contextual help: display code tooltip, improved empty states
- Non-owner aside explanation for hidden owner-only sections
- Admin sidebar: group 11 items into 5 labeled sections
- Rename UsersPage.tsx → AccountsPage.tsx to match route
- Fix border radius consistency, hide zero-count badges

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: use get_admin_db for all new admin account endpoints

All admin endpoints query across tenants without a tenant context.
get_db (app-role, subject to RLS) was never imported and would crash
at runtime — replace all 6 occurrences with get_admin_db (BYPASSRLS).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/types/admin.ts

@@ -18,6 +18,108 @@ export interface ActivityEntry {
   created_at: string
 }
 
+export interface AdminUserListItem {
+  id: string
+  email: string
+  name: string
+  role: string
+  is_super_admin: boolean
+  is_active: boolean
+  account_id: string | null
+  account_role: string | null
+  account_name: string | null
+  account_display_code: string | null
+  created_at: string
+  last_login: string | null
+  deleted_at: string | null
+}
+
+export interface AdminUserListResponse {
+  items: AdminUserListItem[]
+  total: number
+  page: number
+  per_page: number
+}
+
+export interface AdminAccountMember {
+  id: string
+  email: string
+  name: string
+  role: string
+  is_super_admin: boolean
+  is_active: boolean
+  account_role: string | null
+  created_at: string
+  last_login: string | null
+  deleted_at: string | null
+}
+
+export interface AdminAccountOwnerSummary {
+  id: string
+  name: string
+  email: string
+}
+
+export interface AdminAccountSubscriptionSummary {
+  id: string
+  plan: string
+  status: string
+  billing_interval: string | null
+  current_period_end: string | null
+  cancel_at_period_end: boolean
+}
+
+export interface AdminAccountUsageSummary {
+  tree_count: number
+  session_count_this_month: number
+}
+
+export interface AdminAccountListItem {
+  id: string
+  name: string
+  display_code: string
+  created_at: string
+  owner_id: string | null
+  owner: AdminAccountOwnerSummary | null
+  subscription: AdminAccountSubscriptionSummary | null
+  usage: AdminAccountUsageSummary
+  member_count: number
+  active_member_count: number
+  pending_invite_count: number
+  sso_enabled: boolean
+  branding_company_name: string | null
+  members: AdminAccountMember[]
+}
+
+export interface AdminAccountListResponse {
+  items: AdminAccountListItem[]
+  total: number
+  page: number
+  per_page: number
+}
+
+export interface AdminAccountInviteSummary {
+  id: string
+  email: string
+  role: string
+  expires_at: string | null
+  created_at: string
+  used_at: string | null
+}
+
+export interface AdminAccountDetailResponse extends AdminAccountListItem {
+  invites: AdminAccountInviteSummary[]
+}
+
+export interface AdminAccountCreate {
+  name: string
+  plan: 'free' | 'pro' | 'team'
+}
+
+export interface AdminAccountUpdate {
+  name: string
+}
+
 export interface AuditLogEntry {
   id: string
   user_id: string