fix: enforce read-only restrictions for viewer role across 5 pages

Audit and fix viewer (read-only) user permissions:
- Dashboard: hide health score refresh buttons
- Accounts: hide investment edit icons
- Invoices: hide Apply Late Fees and Generate Invoices buttons
- Capital Planning: disable drag-and-drop, hide grip handles and edit buttons
- Investment Planning: hide AI Recommendations refresh button

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

frontend/src/pages/accounts/AccountsPage.tsx

@@ -587,7 +587,7 @@ export function AccountsPage() {
             {investments.filter(i => i.is_active).length > 0 && (
               <>
                 <Divider label="Investment Accounts" labelPosition="center" my="xs" />
-                <InvestmentMiniTable investments={investments.filter(i => i.is_active)} onEdit={handleEditInvestment} />
+                <InvestmentMiniTable investments={investments.filter(i => i.is_active)} onEdit={handleEditInvestment} isReadOnly={isReadOnly} />
               </>
             )}
           </Stack>
@@ -605,7 +605,7 @@ export function AccountsPage() {
             {operatingInvestments.length > 0 && (
               <>
                 <Divider label="Operating Investment Accounts" labelPosition="center" my="xs" />
-                <InvestmentMiniTable investments={operatingInvestments} onEdit={handleEditInvestment} />
+                <InvestmentMiniTable investments={operatingInvestments} onEdit={handleEditInvestment} isReadOnly={isReadOnly} />
               </>
             )}
           </Stack>
@@ -623,7 +623,7 @@ export function AccountsPage() {
             {reserveInvestments.length > 0 && (
               <>
                 <Divider label="Reserve Investment Accounts" labelPosition="center" my="xs" />
-                <InvestmentMiniTable investments={reserveInvestments} onEdit={handleEditInvestment} />
+                <InvestmentMiniTable investments={reserveInvestments} onEdit={handleEditInvestment} isReadOnly={isReadOnly} />
               </>
             )}
           </Stack>
@@ -1087,9 +1087,11 @@ function AccountTable({
 function InvestmentMiniTable({
   investments,
   onEdit,
+  isReadOnly = false,
 }: {
   investments: Investment[];
   onEdit: (inv: Investment) => void;
+  isReadOnly?: boolean;
 }) {
   const totalPrincipal = investments.reduce((s, i) => s + parseFloat(i.principal || '0'), 0);
   const totalValue = investments.reduce(
@@ -1132,7 +1134,7 @@ function InvestmentMiniTable({
             <Table.Th ta="right">Maturity Value</Table.Th>
             <Table.Th>Maturity Date</Table.Th>
             <Table.Th ta="right">Days Remaining</Table.Th>
-            <Table.Th></Table.Th>
+            {!isReadOnly && <Table.Th></Table.Th>}
           </Table.Tr>
         </Table.Thead>
         <Table.Tbody>
@@ -1182,13 +1184,15 @@ function InvestmentMiniTable({
                   '-'
                 )}
               </Table.Td>
-              <Table.Td>
-                <Tooltip label="Edit investment">
-                  <ActionIcon variant="subtle" onClick={() => onEdit(inv)}>
-                    <IconEdit size={16} />
-                  </ActionIcon>
-                </Tooltip>
-              </Table.Td>
+              {!isReadOnly && (
+                <Table.Td>
+                  <Tooltip label="Edit investment">
+                    <ActionIcon variant="subtle" onClick={() => onEdit(inv)}>
+                      <IconEdit size={16} />
+                    </ActionIcon>
+                  </Tooltip>
+                </Table.Td>
+              )}
             </Table.Tr>
           ))}
         </Table.Tbody>