Enables equity eligibility for users

Allows superusers to grant and revoke equity eligibility for users.
Adds UI components for managing equity eligibility.
Equity-eligible users can then contribute expenses as equity.

templates/castle/index.html

@@ -723,6 +723,7 @@
       ></q-select>
 
       <q-select
+        v-if="userInfo && userInfo.is_equity_eligible"
         filled
         dense
         v-model="expenseDialog.isEquity"
@@ -735,8 +736,25 @@
         emit-value
         map-options
         label="Type *"
+        hint="Choose whether this is a liability (Castle owes you) or an equity contribution"
       ></q-select>
 
+      <!-- If user is not equity eligible, force liability -->
+      <div v-else>
+        <q-input
+          filled
+          dense
+          readonly
+          :model-value="'Liability (Castle owes me)'"
+          label="Type"
+          hint="This expense will be recorded as a liability (Castle owes you)"
+        >
+          <template v-slot:prepend>
+            <q-icon name="info" color="blue-grey-7"></q-icon>
+          </template>
+        </q-input>
+      </div>
+
       <q-input
         filled
         dense