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/src/lib/callToPlay.ts

@@ -9,6 +9,12 @@ export const CHECKIN_LEAD_MS = 15 * 60_000;
 export const EXPIRED_RETENTION_MS = 5 * 60_000;
 export const TERMINAL_RETENTION_MS = 15 * 60_000;
 
+export const extendDeadline = (
+    now: number,
+    currentDeadline: number,
+    durationMinutes = 5,
+): number => Math.max(now, currentDeadline) + durationMinutes * 60_000;
+
 export type CallToPlayPhase = 'now' | 'scheduled' | 'checkin';
 export type CallToPlayStatus =
     | 'running'