feat(android): configurable incoming/outgoing call timeout via CallkeepAndroidOptions

[SERDUN]

Summary

• Adds incomingCallTimeoutMs and outgoingCallTimeoutMs to CallkeepAndroidOptions so callers can configure how long the app waits before auto-disconnecting an unanswered call
• Default is 60 000 ms (both Dart constructor and native fallback), up from the previous hardcoded 35 000 ms
• Values are persisted via StorageDelegate.Timeout and read by ConnectionTimeout factory methods at connection creation time — no change needed to call sites beyond passing context
• Generated Pigeon files (callkeep.pigeon.dart, Generated.kt) regenerated via flutter pub run pigeon

Motivation

PortaSIP terminates unanswered calls after 120 s. The previous 35 s hardcoded timeout caused CallKeep to disconnect calls on the Android side well before PortaSIP acted, resulting in unexpected early hang-ups (see WT-1273).

Usage

android: CallkeepAndroidOptions(
  ringtoneSound: Assets.ringtones.incomingCall1,
  ringbackSound: Assets.ringtones.outgoingCall1,
  incomingCallTimeoutMs: 120000,  // align with PortaSIP
  outgoingCallTimeoutMs: 120000,
),

Test plan

• Incoming call — do not answer — verify call stays active for at least 60 s before auto-disconnect
• Outgoing call — remote does not answer — verify caller stays in DIALING for at least 60 s
• Pass explicit incomingCallTimeoutMs: 120000 — verify timeout fires after 120 s
• Omit the fields — verify default 60 s behaviour

Fixes WT-1273