Cherry-pick from upstream

• Commit: b4c895041
• Author: steipete
• Tier: AUTO-PARTIAL

Summary

Centralizes talk silence timeout defaults into dedicated TalkDefaults constants on each platform (Android, iOS, macOS) and a new src/config/talk-defaults.ts module for the gateway. Adds a cross-platform consistency test that verifies help text, docs, and native constants all agree on the default values.

Adaptation

• Rebranded Android TalkDefaults.kt package from ai.openclaw.app.voice to org.remoteclaw.android.voice
• New file placed at rebranded macOS path (Sources/RemoteClaw/ instead of Sources/OpenClaw/)
• Updated test file paths in talk-defaults.test.ts to use rebranded directory structure
• Resolved conflict in schema.help.ts to accept upstream's template literal while preserving fork's gutted ACP entries
• Preserved fork's __REMOTECLAW_REDACTED__ sentinel in iOS TalkModeManager.swift
• Added silence timeout tests to Android test file (not present in fork HEAD, upstream semantic change applied)

Depends on #1275.
Cherry-picked from openclaw/openclaw per #902.