v3.20.0: the server-owned SCP80 counter (an untouched field = the preset's next value)

The counter an operation consumed was re-entered by the PWA on every send
(the form field was filled from the preset and posted back), so a stale tab
could send a value the card rejects (cntr_low), and typing in the field
silently wrote the preset.  Now the store is the single source of truth and
the form field is a per-send override (Option B).

- _preset_counter_seed: an explicit `cntr` in the request wins (a hand send,
  the counter probe or a pre-built packet may deliberately pick one);
  otherwise the preset store's value for the packet's keyset.  Wired into
  /api/send-ota (the APDU path; the pre-built `sp` path keeps the caller's
  bookkeeping value - the packet carries its own counter), /api/ram-install,
  /api/ram-install-app, /api/cap-compat, /api/tar-probe and /api/sp-verify
  (the reference must use the counter the JS packet was built with).
- the send-ota response echoes the effective `cntr` (a caller that omitted
  one learns what was used) and the OTA SEND log line prints it.
- persistence is unchanged and monotonic (presets.set_counter refuses
  backwards writes), pinned by tests: an explicit lower counter is used for
  the packet but never lowers the store, a higher accepted one is saved.
- PWA: the Secured packet counter field starts empty with the preset's next
  value as its placeholder (auto: <cntr>); typing affects that send only and
  is never written to the preset (spCntrSyncPreset is gone), spParams /
  getRamSpParams omit an empty counter, the RAM/send flows sync only the
  local preset copy (forward-only) instead of filling the field, the +/-
  buttons start from the effective value, and the preview/verify packet is
  built from the effective counter (genSp).  Placeholder translated EN/RU.
- the runner and /api/counter-probe keep their existing seeding (the probe
  already starts at the failed value and walks above it).
- docs: api.md's optional-`cntr` contract + seeding notes on every endpoint,
  help EN/RU 3.1.  Tests: 822 frontend + 734 Python; sw cache simple-v393.

frontend/tests/cards_form.test.js

@@ -31,7 +31,8 @@ let code = '';
 const ASYNC_FNS = ['cardsAdd', 'cardsImport', 'cardsRemove'];
 for (const fn of ['cardsFormValues', 'cardsClearForm', 'cardsEdit',
 	'cardsAdd', 'cardsImport', 'cardsRemove', 'ramCardIdxAfterRemove',
-	'spPresetIdx', 'spCntrSyncPreset', 'spCntrLocalSync', 'ramSaveCntr',
+	'spPresetIdx', 'spPresetCounterValue', 'spCntrPlaceholder', 'spCntrEffective',
+	'spCntrAhead', 'spCntrLocalSync', 'ramSaveCntr',
 	'cardsApplyFields', 'cardsApply', 'ramApplyCard',
 	'cardsScp80Complete', 'cardsScp81Complete', 'cardsAdmPresent',
 	'spTarKeyForPack', 'spPresetTar', 'spTarListRender', 'packToSp',
@@ -415,29 +416,25 @@ test('import posts the entries to the server store', async () => {
 	assert.strictEqual(apiCalls.length, 0);
 });
 
-test('the SCP80 counter edit is written to the store, a reported counter only locally', () => {
+test('the SCP80 counter field is an override - an edit is never written to the store', () => {
 	const els = setup();
 	globalThis.cards = [{ id: 'abc123', name: 'C', keysets: [
 		{ kic: '15', kid: '15', kicKey: 'AA', kidKey: 'BB', cntr: '0000000001' }] }];
 	els['sp-card-sel'].value = '0';
 	els['sp-kic-hex'].value = '15';
 	els['sp-kid-hex'].value = '15';
-	els['sp-cntr'].value = '0000000009';
-	assert.strictEqual(spCntrSyncPreset(), true);
-	assert.strictEqual(cards[0].keysets[0].cntr, '0000000009');
-	assert.strictEqual(apiCalls.length, 1);
-	assert.strictEqual(apiCalls[0].path, '/api/presets/update');
-	assert.strictEqual(apiCalls[0].body.id, 'abc123');
-	assert.strictEqual(apiCalls[0].body.fields.keysets[0].cntr, '0000000009');
-	// a counter the server already persisted: display only, no second write
-	apiCalls = [];
+	els['sp-cntr'].value = '0000000009';           // an explicit override
+	// typing alone writes nothing (no spCntrSyncPreset anymore, v3.20.0)
+	assert.strictEqual(apiCalls.length, 0);
+	// a counter the server persisted: the local copy moves forward, display only
 	spCntrLocalSync('000000000A');
 	assert.strictEqual(cards[0].keysets[0].cntr, '000000000A');
 	assert.strictEqual(apiCalls.length, 0);
-	// no preset selected: nothing to write
-	els['sp-card-sel'].value = '';
-	assert.strictEqual(spCntrSyncPreset(), false);
-	assert.strictEqual(apiCalls.length, 0);
+	// and the copy never regresses (the store is monotonic)
+	spCntrLocalSync('0000000005');
+	assert.strictEqual(cards[0].keysets[0].cntr, '000000000A');
+	// the override in the field is untouched by the copy sync
+	assert.strictEqual(els['sp-cntr'].value, '0000000009');
 });
 
 test('applying a preset uses the TAR of the current operation and seeds the SPI1 from its MSL', () => {