refactor(ssr): collapse 5 manual-coding operation routes into edit-form-changed (heuristic 6)

The 5 manual-coding operations (vendor change, simple/advanced toggle, add row, remove
row, $/% toggle) each had their own route + handler, all doing "mutate form state ->
render-full-form". Fold them into the single edit-form-changed endpoint, which now
dispatches on an `op` form-param to the relevant pure apply-* mutation fn (apply-vendor-
changed / apply-toggle-mode / apply-new-account / apply-remove-account /
apply-toggle-amount-mode) then re-renders. A missing/unknown op (a plain dependent-field
change, e.g. account->location or amount->totals) just re-renders, as before.

- edit.clj: 6 handlers -> 1 dispatcher + 5 pure apply-* fns; markup posts to
  edit-form-changed with :hx-vals {:op "..."}.
- routes/transactions.cljc: remove the 5 now-unused route keys.
- e2e specs: retarget the vendor selector by op (div[hx-vals*="vendor-changed"]) and
  point the toggle-amount-mode / vendor response waits at edit-form-changed, since the
  old per-op route names are gone. (Behavioral assertions unchanged.)

Scorecard: manual-coding routes ~10 -> ~5 (operations now one dispatcher). Parity held:
swap spec 6/6, full suite 32 pass (Shared Location green; no new regression).

e2e/transaction-edit.spec.ts

@@ -150,7 +150,7 @@ async function toggleToPercentMode(page: any) {
   
   // Wait for HTMX to swap the grid body
   await page.waitForResponse(response => 
-    response.url().includes('/toggle-amount-mode') && response.status() === 200
+    response.url().includes('/edit-form-changed') && response.status() === 200
   );
   await page.waitForTimeout(200);
 }
@@ -161,7 +161,7 @@ async function toggleToDollarMode(page: any) {
   
   // Wait for HTMX to swap the grid body
   await page.waitForResponse(response => 
-    response.url().includes('/toggle-amount-mode') && response.status() === 200
+    response.url().includes('/edit-form-changed') && response.status() === 200
   );
   await page.waitForTimeout(200);
 }
@@ -359,7 +359,7 @@ async function selectVendorFromTypeahead(page: any, vendorName: string) {
     throw new Error(`Could not find vendor with name ${vendorName}`);
   }
 
-  const vendorContainer = page.locator('div[hx-post*="edit-vendor-changed"]').first();
+  const vendorContainer = page.locator('div[hx-vals*="vendor-changed"]').first();
   const vendorHidden = vendorContainer.locator('input[type="hidden"]').first();
 
   await vendorHidden.evaluate((el: HTMLInputElement, value: string) => {
@@ -374,7 +374,7 @@ async function selectVendorFromTypeahead(page: any, vendorName: string) {
     el.dispatchEvent(new Event('change', { bubbles: true }));
   });
 
-  await page.waitForResponse(response => response.url().includes('/edit-vendor-changed') && response.status() === 200);
+  await page.waitForResponse(response => response.url().includes('/edit-form-changed') && response.status() === 200);
   await page.waitForTimeout(500);
 }
 
@@ -434,11 +434,11 @@ test.describe('Transaction Edit Vendor Pre-population', () => {
 // `elements` instead of being fetched. Everything else -- the dropdown's own
 // search input firing a native `change` on blur, the `value = element` click
 // handler, the Alpine reactivity, and the HTMX round-trip to
-// `edit-vendor-changed` -- runs exactly as in production. This is the flow that
+// `edit-form-changed` (op=vendor-changed) -- runs exactly as in production. This is the flow that
 // regressed: a stale native `change` from the search input used to win the race
 // and revert the vendor to its previous value.
 async function selectVendorViaDropdown(page: any, vendorId: number, vendorName: string) {
-  const wrapper = page.locator('div[hx-post*="edit-vendor-changed"]').first();
+  const wrapper = page.locator('div[hx-vals*="vendor-changed"]').first();
   const typeahead = wrapper.locator('div.relative[x-data]').first();
 
   // Open the dropdown (tippy renders the popper into [data-tippy-root]).
@@ -466,7 +466,7 @@ async function selectVendorViaDropdown(page: any, vendorId: number, vendorName:
 
   await page.waitForResponse(
     (response: any) =>
-      response.url().includes('/edit-vendor-changed') && response.status() === 200
+      response.url().includes('/edit-form-changed') && response.status() === 200
   );
   await page.waitForTimeout(500);
 }
@@ -485,7 +485,7 @@ async function openManualVendorSection(page: any, transactionIndex: number) {
   await page.waitForSelector('#modal-holder[x-show="open"]', { state: 'visible' });
   await page.waitForSelector('#wizardmodal');
   await page.click('button:has-text("Manual")');
-  await page.waitForSelector('div[hx-post*="edit-vendor-changed"]');
+  await page.waitForSelector('div[hx-vals*="vendor-changed"]');
 }
 
 test.describe('Transaction Edit Vendor Selection', () => {
@@ -501,14 +501,14 @@ test.describe('Transaction Edit Vendor Selection', () => {
     // round-trip. Before the fix this reverted to blank because a stale
     // `change` event submitted the previous vendor and its response won.
     const label = page
-      .locator('div[hx-post*="edit-vendor-changed"] span[x-text="value.label"]')
+      .locator('div[hx-vals*="vendor-changed"] span[x-text="value.label"]')
       .first();
     await expect(label).toHaveText('Test Vendor');
 
     // The server-rendered hidden input must carry the newly selected vendor id.
     const hidden = page
       .locator(
-        'div[hx-post*="edit-vendor-changed"] input[type="hidden"][name="step-params[transaction/vendor]"]'
+        'div[hx-vals*="vendor-changed"] input[type="hidden"][name="step-params[transaction/vendor]"]'
       )
       .first();
     await expect(hidden).toHaveValue(vendorId.toString());