feat(hr): add employees from the dashboard

Previously the only Employee records were the Owner (created at café signup) and
one Manager per branch — there was no way to add a waiter/cashier/chef. Adds it.

Backend:
- POST /api/cafes/{cafeId}/employees (HrController). Owner/Manager only; creating a
  Manager requires Owner; Owner cannot be created here. Validates name/phone/role,
  enforces one-employee-per-phone, validates branch belongs to the café, and can
  optionally set username/password login in the same step (same hashing + uniqueness
  as the credentials endpoint). Returns EmployeeSummaryDto.

Dashboard:
- New "Team" tab on the HR screen (now the default): employee roster (name, role,
  phone, base salary) + an "Add employee" button (owner/manager) opening an inline
  form — name, phone, role, optional branch, optional base salary, optional login.
- Role labels + all form strings in fa/en/ar.

86 API tests pass; dashboard tsc + build clean.

web/dashboard/messages/en.json

@@ -431,7 +431,8 @@
       "leave": "Leave",
       "payroll": "Payroll",
       "access": "Branch access",
-      "credentials": "Login credentials"
+      "credentials": "Login credentials",
+      "team": "Team"
     },
     "myAttendance": "My attendance",
     "clockIn": "Clock in",
@@ -456,6 +457,33 @@
       "saved": "Credentials saved.",
       "removed": "Credentials removed.",
       "usernameTaken": "This username is already taken."
+    },
+    "addEmployee": "Add employee",
+    "noEmployees": "No employees yet.",
+    "employeeCreated": "Employee added",
+    "save": "Save",
+    "cancel": "Cancel",
+    "fields": {
+      "name": "Name",
+      "phone": "Mobile",
+      "role": "Role",
+      "branch": "Branch",
+      "branchOptional": "optional",
+      "noBranch": "No branch",
+      "baseSalary": "Base salary (Toman)",
+      "optional": "optional",
+      "enableLogin": "Create username & password",
+      "username": "Username",
+      "password": "Password",
+      "passwordHint": "At least 8 characters"
+    },
+    "roles": {
+      "Owner": "Owner",
+      "Manager": "Manager",
+      "Cashier": "Cashier",
+      "Waiter": "Waiter",
+      "Chef": "Chef",
+      "Delivery": "Delivery"
     }
   },
   "reviews": {