fix(call-to-play): extend from the current deadline

Pass the effective nomination deadline into the Add time action and extend
from whichever is later: that deadline or the current time. This preserves
remaining time when a call becomes ready early while still giving an overdue
call a fresh five-minute window.

Test Plan:
- just fmt
- just frontend-test
- just build
- git diff --cached --check

crates/lanspread-tauri-deno-ts/tests/callToPlay.test.ts

@@ -3,6 +3,7 @@ import {
     EXPIRED_RETENTION_MS,
     TERMINAL_RETENTION_MS,
     activeCallCount,
+    extendDeadline,
     phaseOf,
     bumpTime,
     normalizeTimeInput,
@@ -163,6 +164,20 @@ Deno.test('creator can extend, start, and cancel a call', () => {
     assertEquals(cancelled.terminalAt, NOW + 1, 'cancel timestamp');
 });
 
+Deno.test('adding time extends from the current deadline or the current time', () => {
+    const futureDeadline = NOW + 30 * 60_000;
+    assertEquals(
+        extendDeadline(NOW, futureDeadline),
+        futureDeadline + 5 * 60_000,
+        'ready-early call keeps its remaining time',
+    );
+    assertEquals(
+        extendDeadline(NOW, NOW - 60_000),
+        NOW + 5 * 60_000,
+        'overdue call gets five minutes from now',
+    );
+});
+
 Deno.test('reduction is order-independent and deduplicates events and messages', () => {
     const message = event('message-event', 'Bob', {
         SendMessage: { message_id: 'message-1', text: 'Ready?' },