Quality-of-life enhancements: CSV import/export, opening balances, interest rates, mobile UX

- CSV import/export for Units, Projects, and Vendors with match-on-name/number upsert
- Cash Flow report toggle for Cash Only vs Cash + Investments
- Per-account and bulk opening balance setting with as-of date
- Interest rate field on normal accounts with estimated monthly/annual interest display
- Mobile sidebar auto-close on navigation
- Shared CSV parsing/export utility extracted to frontend/src/utils/csv.ts

DB migration needed for existing tenants:
  ALTER TABLE accounts ADD COLUMN IF NOT EXISTS interest_rate DECIMAL(6,4);

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

backend/src/modules/vendors/vendors.controller.ts

@@ -1,5 +1,6 @@
-import { Controller, Get, Post, Put, Body, Param, Query, UseGuards } from '@nestjs/common';
+import { Controller, Get, Post, Put, Body, Param, Query, Res, UseGuards } from '@nestjs/common';
 import { ApiTags, ApiBearerAuth } from '@nestjs/swagger';
+import { Response } from 'express';
 import { JwtAuthGuard } from '../auth/guards/jwt-auth.guard';
 import { VendorsService } from './vendors.service';
 
@@ -13,6 +14,13 @@ export class VendorsController {
   @Get()
   findAll() { return this.vendorsService.findAll(); }
 
+  @Get('export')
+  async exportCSV(@Res() res: Response) {
+    const csv = await this.vendorsService.exportCSV();
+    res.set({ 'Content-Type': 'text/csv', 'Content-Disposition': 'attachment; filename="vendors.csv"' });
+    res.send(csv);
+  }
+
   @Get('1099-data')
   get1099Data(@Query('year') year: string) {
     return this.vendorsService.get1099Data(parseInt(year) || new Date().getFullYear());
@@ -21,6 +29,9 @@ export class VendorsController {
   @Get(':id')
   findOne(@Param('id') id: string) { return this.vendorsService.findOne(id); }
 
+  @Post('import')
+  importCSV(@Body() rows: any[]) { return this.vendorsService.importCSV(rows); }
+
   @Post()
   create(@Body() dto: any) { return this.vendorsService.create(dto); }
 

backend/src/modules/vendors/vendors.service.ts

@@ -40,6 +40,70 @@ export class VendorsService {
     return rows[0];
   }
 
+  async exportCSV(): Promise<string> {
+    const rows = await this.tenant.query(
+      `SELECT name, contact_name, email, phone, address_line1, city, state, zip_code, tax_id, is_1099_eligible
+       FROM vendors WHERE is_active = true ORDER BY name`,
+    );
+    const headers = ['name', 'contact_name', 'email', 'phone', 'address_line1', 'city', 'state', 'zip_code', 'tax_id', 'is_1099_eligible'];
+    const lines = [headers.join(',')];
+    for (const r of rows) {
+      lines.push(headers.map((h) => {
+        const v = r[h] ?? '';
+        const s = String(v);
+        return s.includes(',') || s.includes('"') ? `"${s.replace(/"/g, '""')}"` : s;
+      }).join(','));
+    }
+    return lines.join('\n');
+  }
+
+  async importCSV(rows: any[]) {
+    let created = 0, updated = 0;
+    const errors: string[] = [];
+
+    for (let i = 0; i < rows.length; i++) {
+      const row = rows[i];
+      const name = (row.name || '').trim();
+      if (!name) { errors.push(`Row ${i + 1}: missing name (required)`); continue; }
+
+      try {
+        const existing = await this.tenant.query('SELECT id FROM vendors WHERE name = $1 AND is_active = true', [name]);
+        if (existing.length) {
+          await this.tenant.query(
+            `UPDATE vendors SET
+              contact_name = COALESCE(NULLIF($2, ''), contact_name),
+              email = COALESCE(NULLIF($3, ''), email),
+              phone = COALESCE(NULLIF($4, ''), phone),
+              address_line1 = COALESCE(NULLIF($5, ''), address_line1),
+              city = COALESCE(NULLIF($6, ''), city),
+              state = COALESCE(NULLIF($7, ''), state),
+              zip_code = COALESCE(NULLIF($8, ''), zip_code),
+              tax_id = COALESCE(NULLIF($9, ''), tax_id),
+              is_1099_eligible = COALESCE(NULLIF($10, '')::boolean, is_1099_eligible),
+              updated_at = NOW()
+             WHERE id = $1`,
+            [existing[0].id, row.contact_name, row.email, row.phone, row.address_line1,
+             row.city, row.state, row.zip_code, row.tax_id, row.is_1099_eligible],
+          );
+          updated++;
+        } else {
+          await this.tenant.query(
+            `INSERT INTO vendors (name, contact_name, email, phone, address_line1, city, state, zip_code, tax_id, is_1099_eligible)
+             VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)`,
+            [name, row.contact_name || null, row.email || null, row.phone || null,
+             row.address_line1 || null, row.city || null, row.state || null,
+             row.zip_code || null, row.tax_id || null,
+             row.is_1099_eligible === 'true' || row.is_1099_eligible === true || false],
+          );
+          created++;
+        }
+      } catch (err: any) {
+        errors.push(`Row ${i + 1} (${name}): ${err.message}`);
+      }
+    }
+    return { imported: created + updated, created, updated, errors };
+  }
+
   async get1099Data(year: number) {
     return this.tenant.query(`
       SELECT v.*, COALESCE(SUM(p_amounts.amount), 0) as total_paid