Add vendor pre-population for bulk code and individual edit forms

- Add vendor-changed HTMX handlers for both bulk code and individual edit
- Pre-populate default account at 100% when vendor is selected and no accounts exist
- Fix render-accounts-section to render from step-params correctly
- Change bulk code vendor-changed from hx-get to hx-post to include form data
- Add routes for vendor-changed endpoints
- Update e2e tests to cover vendor pre-population
- Run lein cljfmt fix across codebase

e2e/bulk-code-transactions.spec.ts

@@ -375,7 +375,6 @@ test.describe('Bulk Code Transactions - Account Distribution', () => {
     
     await addNewAccount(page);
     await selectAccountFromTypeahead(page, 0, 'test-account');
-    // "Shared" should be valid for accounts without fixed location
     await setAccountLocation(page, 0, 'Shared');
     await setAccountPercentage(page, 0, '100');
     
@@ -385,3 +384,60 @@ test.describe('Bulk Code Transactions - Account Distribution', () => {
     await page.waitForSelector('table tbody tr');
   });
 });
+
+test.describe('Bulk Code Transactions - Vendor Pre-population', () => {
+  test('should pre-populate default account when vendor is selected', async ({ page }) => {
+    await navigateToTransactions(page);
+    await selectTransactionByIndex(page, 0);
+    await openBulkCodeModal(page);
+    
+    // Select vendor (test vendor has default-account set to test-account)
+    const testInfo = await getTestInfo(page);
+    const vendorId = testInfo.accounts.vendor;
+    
+    // The vendor typeahead dispatches change from its parent div
+    // We need to set the hidden input and dispatch change on the container
+    const vendorContainer = page.locator('div[hx-post*="vendor-changed"]').first();
+    const vendorHidden = vendorContainer.locator('input[type="hidden"]').first();
+    
+    await vendorHidden.evaluate((el: HTMLInputElement, value: string) => {
+      const newInput = document.createElement('input');
+      newInput.type = 'hidden';
+      newInput.name = el.name;
+      newInput.value = value;
+      el.parentNode.replaceChild(newInput, el);
+    }, vendorId.toString());
+    
+    // Dispatch change on the container to trigger HTMX
+    await vendorContainer.evaluate((el: HTMLElement) => {
+      el.dispatchEvent(new Event('change', { bubbles: true }));
+    });
+    
+    // Wait for HTMX response
+    await page.waitForResponse(response => response.url().includes('/vendor-changed') && response.status() === 200);
+    await page.waitForTimeout(500);
+    
+    // Account should be pre-populated - check for account row
+    const accountRows = page.locator('#account-entries tbody tr');
+    const rowCount = await accountRows.count();
+    
+    // Should have at least 1 account row (the default account) plus the new-row button
+    expect(rowCount).toBeGreaterThanOrEqual(2);
+    
+    // The account should have a hidden input with the test-account ID
+    const accountHidden = page.locator('input[type="hidden"][name*="[account]"]').first();
+    const accountValue = await accountHidden.inputValue();
+    expect(accountValue).toBe(testInfo.accounts['test-account'].toString());
+    
+    // Percentage should be 100
+    const percentageInput = page.locator('input[name*="percentage"]').first();
+    const percentageValue = await percentageInput.inputValue();
+    expect(percentageValue).toBe('100');
+    
+    // Submit should succeed
+    await submitBulkCodeForm(page);
+    await closeBulkCodeModal(page);
+    
+    await page.waitForSelector('table tbody tr');
+  });
+});