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>

backend/app/schemas/admin.py

@@ -28,6 +28,110 @@ class ActivityEntry(BaseModel):
         from_attributes = True
 
 
+# --- Admin Accounts & People Search ---
+
+class AdminUserListItem(BaseModel):
+    id: UUID
+    email: EmailStr
+    name: str
+    role: str
+    is_super_admin: bool = False
+    is_active: bool = True
+    account_id: Optional[UUID] = None
+    account_role: Optional[str] = None
+    account_name: Optional[str] = None
+    account_display_code: Optional[str] = None
+    created_at: datetime
+    last_login: Optional[datetime] = None
+    deleted_at: Optional[datetime] = None
+
+
+class AdminUserListResponse(BaseModel):
+    items: list[AdminUserListItem]
+    total: int
+    page: int
+    per_page: int
+
+
+class AdminAccountMember(BaseModel):
+    id: UUID
+    email: EmailStr
+    name: str
+    role: str
+    is_super_admin: bool = False
+    is_active: bool = True
+    account_role: Optional[str] = None
+    created_at: datetime
+    last_login: Optional[datetime] = None
+    deleted_at: Optional[datetime] = None
+
+
+class AdminAccountOwnerSummary(BaseModel):
+    id: UUID
+    name: str
+    email: EmailStr
+
+
+class AdminAccountSubscriptionSummary(BaseModel):
+    id: UUID
+    plan: str
+    status: str
+    billing_interval: Optional[str] = None
+    current_period_end: Optional[datetime] = None
+    cancel_at_period_end: bool = False
+
+
+class AdminAccountUsageSummary(BaseModel):
+    tree_count: int = 0
+    session_count_this_month: int = 0
+
+
+class AdminAccountInviteSummary(BaseModel):
+    id: UUID
+    email: EmailStr
+    role: str
+    expires_at: Optional[datetime] = None
+    created_at: datetime
+    used_at: Optional[datetime] = None
+
+
+class AdminAccountListItem(BaseModel):
+    id: UUID
+    name: str
+    display_code: str
+    created_at: datetime
+    owner_id: Optional[UUID] = None
+    owner: Optional[AdminAccountOwnerSummary] = None
+    subscription: Optional[AdminAccountSubscriptionSummary] = None
+    usage: AdminAccountUsageSummary = Field(default_factory=AdminAccountUsageSummary)
+    member_count: int = 0
+    active_member_count: int = 0
+    pending_invite_count: int = 0
+    sso_enabled: bool = False
+    branding_company_name: Optional[str] = None
+    members: list[AdminAccountMember] = Field(default_factory=list)
+
+
+class AdminAccountListResponse(BaseModel):
+    items: list[AdminAccountListItem]
+    total: int
+    page: int
+    per_page: int
+
+
+class AdminAccountDetailResponse(AdminAccountListItem):
+    invites: list[AdminAccountInviteSummary] = Field(default_factory=list)
+
+
+class AdminAccountCreate(BaseModel):
+    name: str = Field(..., min_length=1, max_length=255)
+    plan: Literal["free", "pro", "team"] = "free"
+
+
+class AdminAccountUpdate(BaseModel):
+    name: str = Field(..., min_length=1, max_length=255)
+
+
 # --- Audit Logs ---
 
 class AuditLogEntry(BaseModel):