Allow per-player delay configuration

[maximmaxim345]

Players report static_delay_ms in client/state (always present, 0-5000ms range). Servers can adjust it via set_static_delay command for players that list it in supported_commands in the player roles client/state object.

Clients subtract static_delay_ms from server timestamps before scheduling playback (a 300ms delay means external equipment has 300ms latency, so playback starts earlier). Servers factor it into buffer calculations to maintain headroom. Value persists locally across reboots.

Example implementations

Scenario	static_delay_ms	set_static_delay supported
DIY speaker without pre-calibrated delay	User adjustable	Yes
Ready-made speaker with factory-measured delay	0	No
Active speakers connected to pre-calibrated audio port	Delay matching speaker latency	Yes
Active speakers with delay measured outside Sendspin	Read-only value for buffer optimization	No

Limitations

• No way to reduce server buffer headroom for devices with inherent internal delay (e.g., 100ms DAC/DSP). Since 0 must remain the default baseline, that 100ms cannot be reclaimed. We will accept that players with a high latency DAC/DSP will need to advertise a larger buffer_capacity and compensate that themselves.

[kahrendt]

LGTM