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/projects/projects.service.ts

@@ -176,6 +176,87 @@ export class ProjectsService {
     return rows[0];
   }
 
+  async exportCSV(): Promise<string> {
+    const rows = await this.tenant.query(
+      `SELECT name, description, category, estimated_cost, actual_cost, fund_source,
+        useful_life_years, remaining_life_years, condition_rating,
+        last_replacement_date, next_replacement_date, planned_date,
+        target_year, target_month, status, priority, notes
+       FROM projects WHERE is_active = true ORDER BY name`,
+    );
+    const headers = ['*name', 'description', '*category', '*estimated_cost', 'actual_cost', 'fund_source',
+      'useful_life_years', 'remaining_life_years', 'condition_rating',
+      'last_replacement_date', 'next_replacement_date', 'planned_date',
+      'target_year', 'target_month', 'status', 'priority', 'notes'];
+    const keys = headers.map(h => h.replace(/^\*/, ''));
+    const lines = [headers.join(',')];
+    for (const r of rows) {
+      lines.push(keys.map((k) => {
+        let v = r[k] ?? '';
+        if (v instanceof Date) v = v.toISOString().split('T')[0];
+        const s = String(v);
+        return s.includes(',') || s.includes('"') || s.includes('\n') ? `"${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; }
+      if (!row.category) { errors.push(`Row ${i + 1}: missing category (required)`); continue; }
+      if (!row.estimated_cost) { errors.push(`Row ${i + 1}: missing estimated_cost (required)`); continue; }
+
+      try {
+        const existing = await this.tenant.query('SELECT id FROM projects WHERE name = $1 AND is_active = true', [name]);
+        if (existing.length) {
+          const sets: string[] = [];
+          const params: any[] = [existing[0].id];
+          let idx = 2;
+          const fields = ['description', 'category', 'estimated_cost', 'actual_cost', 'fund_source',
+            'useful_life_years', 'remaining_life_years', 'condition_rating',
+            'last_replacement_date', 'next_replacement_date', 'planned_date',
+            'target_year', 'target_month', 'status', 'priority', 'notes'];
+          for (const f of fields) {
+            if (row[f] !== undefined && row[f] !== '') {
+              sets.push(`${f} = $${idx++}`);
+              params.push(row[f]);
+            }
+          }
+          if (sets.length) {
+            sets.push('updated_at = NOW()');
+            await this.tenant.query(`UPDATE projects SET ${sets.join(', ')} WHERE id = $1`, params);
+          }
+          updated++;
+        } else {
+          await this.tenant.query(
+            `INSERT INTO projects (name, description, category, estimated_cost, actual_cost, fund_source,
+              useful_life_years, remaining_life_years, condition_rating,
+              last_replacement_date, next_replacement_date, planned_date,
+              target_year, target_month, status, priority, notes)
+             VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10,$11,$12,$13,$14,$15,$16,$17)`,
+            [name, row.description || null, row.category, parseFloat(row.estimated_cost) || 0,
+             row.actual_cost || null, row.fund_source || 'reserve',
+             row.useful_life_years || null, row.remaining_life_years || null,
+             row.condition_rating || null, row.last_replacement_date || null,
+             row.next_replacement_date || null, row.planned_date || null,
+             row.target_year || null, row.target_month || null,
+             row.status || 'planned', row.priority || 3, row.notes || null],
+          );
+          created++;
+        }
+      } catch (err: any) {
+        errors.push(`Row ${i + 1} (${name}): ${err.message}`);
+      }
+    }
+    return { imported: created + updated, created, updated, errors };
+  }
+
   async updatePlannedDate(id: string, planned_date: string) {
     await this.findOne(id);
     const rows = await this.tenant.query(