Make multi_agent_v2 wait_agent timeouts configurable

[andmis]

Why

multi_agent_v2 already allowed configuring the minimum wait_agent timeout, but the default timeout and upper bound were still hard-coded. That made it hard to tune waits for subagent mailbox activity in sessions that need either faster wakeups or longer waits, and it meant the model-visible wait_agent schema could not fully reflect the resolved runtime limits.

What Changed

• Added features.multi_agent_v2.max_wait_timeout_ms and features.multi_agent_v2.default_wait_timeout_ms alongside the existing min_wait_timeout_ms setting.
• Validated all three timeouts in config as 0..=3_600_000, with min_wait_timeout_ms <= default_wait_timeout_ms <= max_wait_timeout_ms.
• Thread and review session tool config now passes the resolved min/default/max values into the wait_agent tool schema.
• wait_agent now uses the configured default when timeout_ms is omitted and rejects explicit values outside the configured min/max range instead of silently clamping them.
• Updated the generated config schema and config-lock test coverage for the new fields.

[jif-oai]

lgtm