[test](trx-frontend-http): type the frequency instead of filling it

tune-links drove the dial with Playwright's fill(), which writes a value
into the field without a keystroke.  The app arms its guard against its own
refreshes on the first keydown, so a filled field stays unguarded: any state
update landing between the fill and the Enter rewrites the field with the
frequency the radio is already on, and the Enter then re-applies that.  The
window is a few milliseconds wide on a developer's machine and wide enough
to lose on a loaded CI runner, where the test failed claiming the tuning had
landed on the frequency it started from.

Type it the way an operator does: select the field, then send the characters
as keystrokes.  The select arms the guard before a single character changes.

Under CPU throttling that reproduced the failure — 1 in 6 runs with fill(),
on this branch and on main alike — typing came through 8 runs clean.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SyX26FCpMQxiBoC7r5K1A7
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/tune-links.mjs

@@ -27,6 +27,21 @@ const dial = () => page.evaluate(() => ({
   path: window.location.pathname,
 }));
 
+// Typed, not filled. The app holds back its own refreshes of the frequency
+// field from the first keystroke until Enter, so that a state update arriving
+// mid-edit does not rewrite what is being typed. `fill()` sets the value
+// without a keystroke, leaving the field unguarded: on a slow machine a state
+// update could land between the fill and the Enter and put the old frequency
+// back, and the Enter would then re-apply the frequency the radio was already
+// on. Selecting first arms the guard before a single character changes.
+async function tuneByHand(text) {
+  const field = page.locator("#freq");
+  await field.click();
+  await field.press("ControlOrMeta+a");
+  await field.pressSequentially(text);
+  await field.press("Enter");
+}
+
 try {
   await page.setViewportSize({ width: 1500, height: 950 });
 
@@ -49,8 +64,7 @@ try {
 
   // Tuning by hand rewrites the link. This is the part that makes the address
   // bar shareable at any moment rather than only at load.
-  await page.locator("#freq").fill("7.040M");
-  await page.locator("#freq").press("Enter");
+  await tuneByHand("7.040M");
   await page.waitForTimeout(1500);
   const tuned = await dial();
   assert.equal(tuned.freqHz, TUNED_HZ, `tuning landed on ${tuned.freqHz} Hz`);
@@ -59,8 +73,7 @@ try {
 
   // Tuning is not navigation: a swept dial must not bury the back button.
   const historyLength = await page.evaluate(() => window.history.length);
-  await page.locator("#freq").fill("7.100M");
-  await page.locator("#freq").press("Enter");
+  await tuneByHand("7.100M");
   await page.waitForTimeout(1200);
   assert.equal(await page.evaluate(() => window.history.length), historyLength,
     "tuning pushed a history entry instead of replacing one");