Make every identity editable: agent and operator names plus avatars

- Migration 049: avatar_emoji/avatar_color on agents and employees
- updateAgent accepts a new name (mention-name validated) and avatar;
  new updateEmployeeProfile renames the operator and sets their avatar
- Avatars are emoji-on-color tiles (renderer CSP blocks remote images);
  an AvatarDirectoryContext built from the snapshot lets the shared
  Avatar component honor custom looks at every call site - chat rows,
  conversation list, org chart, office card, sidebar - without
  threading props through pages
- Team edit dialog gains Name + avatar editor (CEO included); the
  sidebar foot opens an Edit-profile dialog for the operator
- e2e: rename an agent to a new mention handle with an emoji avatar,
  edit the operator profile, both verified in the live shell

src/shared/desktop-api.ts

@@ -7,6 +7,7 @@ import type {
   CancelProviderResponseInput,
   CreateAgentInput,
   UpdateAgentInput,
+  UpdateEmployeeProfileInput,
   CreateApprovalInput,
   CreateAutomationRuleInput,
   CreateDocumentInput,
@@ -107,6 +108,7 @@ export interface DesktopApi {
   createOrganization(input: CreateOrganizationInput): Promise<DesktopResult<AppSnapshot>>;
   createAgent(input: CreateAgentInput): Promise<DesktopResult<AppSnapshot>>;
   updateAgent(input: UpdateAgentInput): Promise<DesktopResult<AppSnapshot>>;
+  updateEmployeeProfile(input: UpdateEmployeeProfileInput): Promise<DesktopResult<AppSnapshot>>;
   createTask(input: CreateTaskInput): Promise<DesktopResult<AppSnapshot>>;
   updateTask(input: UpdateTaskInput): Promise<DesktopResult<AppSnapshot>>;
   deleteTask(input: DeleteTaskInput): Promise<DesktopResult<AppSnapshot>>;