Bug & tweak sprint: fix financial calculations, add quarterly report, enhance dashboard

- Fix Accounts page: include investment accounts in Est. Monthly Interest calc,
  add Fund column to investment table, split summary cards into Operating/Reserve
- Fix Cash Flow: ending balance now respects includeInvestments toggle
- Fix Budget Manager: separate operating/reserve income in summary cards
- Fix Projects: default sort by planned_date instead of name
- Add Vendors: last_negotiated date field with migration, CSV import/export
- New Quarterly Financial Report: budget vs actuals, over-budget flagging, YTD
- Enhance Dashboard: separate Operating/Reserve fund cards, expanded Quick Stats
  with monthly interest, YTD interest earned, planned capital spend

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

frontend/src/pages/vendors/VendorsPage.tsx

@@ -3,6 +3,7 @@ import {
   Title, Table, Group, Button, Stack, TextInput, Modal,
   Switch, Badge, ActionIcon, Text, Loader, Center,
 } from '@mantine/core';
+import { DateInput } from '@mantine/dates';
 import { useForm } from '@mantine/form';
 import { useDisclosure } from '@mantine/hooks';
 import { notifications } from '@mantine/notifications';
@@ -15,6 +16,7 @@ interface Vendor {
   id: string; name: string; contact_name: string; email: string; phone: string;
   address_line1: string; city: string; state: string; zip_code: string;
   tax_id: string; is_1099_eligible: boolean; is_active: boolean; ytd_payments: string;
+  last_negotiated: string | null;
 }
 
 export function VendorsPage() {
@@ -34,12 +36,19 @@ export function VendorsPage() {
       name: '', contact_name: '', email: '', phone: '',
       address_line1: '', city: '', state: '', zip_code: '',
       tax_id: '', is_1099_eligible: false,
+      last_negotiated: null as Date | null,
     },
     validate: { name: (v) => (v.length > 0 ? null : 'Required') },
   });
 
   const saveMutation = useMutation({
-    mutationFn: (values: any) => editing ? api.put(`/vendors/${editing.id}`, values) : api.post('/vendors', values),
+    mutationFn: (values: any) => {
+      const payload = {
+        ...values,
+        last_negotiated: values.last_negotiated ? values.last_negotiated.toISOString().split('T')[0] : null,
+      };
+      return editing ? api.put(`/vendors/${editing.id}`, payload) : api.post('/vendors', payload);
+    },
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['vendors'] });
       notifications.show({ message: editing ? 'Vendor updated' : 'Vendor created', color: 'green' });
@@ -91,6 +100,7 @@ export function VendorsPage() {
       phone: v.phone || '', address_line1: v.address_line1 || '', city: v.city || '',
       state: v.state || '', zip_code: v.zip_code || '', tax_id: v.tax_id || '',
       is_1099_eligible: v.is_1099_eligible,
+      last_negotiated: v.last_negotiated ? new Date(v.last_negotiated) : null,
     });
     open();
   };
@@ -122,6 +132,7 @@ export function VendorsPage() {
           <Table.Tr>
             <Table.Th>Name</Table.Th><Table.Th>Contact</Table.Th><Table.Th>Email</Table.Th>
             <Table.Th>Phone</Table.Th><Table.Th>1099</Table.Th>
+            <Table.Th>Last Negotiated</Table.Th>
             <Table.Th ta="right">YTD Payments</Table.Th><Table.Th></Table.Th>
           </Table.Tr>
         </Table.Thead>
@@ -133,11 +144,12 @@ export function VendorsPage() {
               <Table.Td>{v.email}</Table.Td>
               <Table.Td>{v.phone}</Table.Td>
               <Table.Td>{v.is_1099_eligible && <Badge color="orange" size="sm">1099</Badge>}</Table.Td>
+              <Table.Td>{v.last_negotiated ? new Date(v.last_negotiated).toLocaleDateString() : '-'}</Table.Td>
               <Table.Td ta="right" ff="monospace">${parseFloat(v.ytd_payments || '0').toFixed(2)}</Table.Td>
               <Table.Td><ActionIcon variant="subtle" onClick={() => handleEdit(v)}><IconEdit size={16} /></ActionIcon></Table.Td>
             </Table.Tr>
           ))}
-          {filtered.length === 0 && <Table.Tr><Table.Td colSpan={7}><Text ta="center" c="dimmed" py="lg">No vendors yet</Text></Table.Td></Table.Tr>}
+          {filtered.length === 0 && <Table.Tr><Table.Td colSpan={8}><Text ta="center" c="dimmed" py="lg">No vendors yet</Text></Table.Td></Table.Tr>}
         </Table.Tbody>
       </Table>
       <Modal opened={opened} onClose={close} title={editing ? 'Edit Vendor' : 'New Vendor'}>
@@ -157,6 +169,7 @@ export function VendorsPage() {
             </Group>
             <TextInput label="Tax ID (EIN/SSN)" {...form.getInputProps('tax_id')} />
             <Switch label="1099 Eligible" {...form.getInputProps('is_1099_eligible', { type: 'checkbox' })} />
+            <DateInput label="Last Negotiated" clearable placeholder="Select date" {...form.getInputProps('last_negotiated')} />
             <Button type="submit" loading={saveMutation.isPending}>{editing ? 'Update' : 'Create'}</Button>
           </Stack>
         </form>