feat(restream): add ConfigWebRTC per-process field

Adds the per-process WebRTC egress toggle + codec/payload-type knobs
described in the M2 spec. Clone() carries it forward. No behavior
change yet \u2014 the subsystem wiring comes later in M2.

restream/app/process.go

@@ -18,6 +18,23 @@ type ConfigIO struct {
 	Cleanup []ConfigIOCleanup `json:"cleanup"`
 }
 
+// ConfigWebRTC carries per-process WebRTC egress settings.
+//
+// When Enabled is true the restream manager will (via the app/webrtc
+// subsystem) append an additional FFmpeg output leg that emits H.264/Opus
+// RTP to a loopback UDP port the subsystem allocates. The subsystem reads
+// that RTP and fans it out to WHEP subscribers.
+type ConfigWebRTC struct {
+	Enabled        bool  `json:"enabled"`
+	VideoPT        uint8 `json:"video_pt"`
+	AudioPT        uint8 `json:"audio_pt"`
+	ForceTranscode bool  `json:"force_transcode"`
+}
+
+// Clone returns a deep copy of the WebRTC config (currently a value copy;
+// provided for symmetry with other Clone methods and future-proofing).
+func (w ConfigWebRTC) Clone() ConfigWebRTC { return w }
+
 func (io ConfigIO) Clone() ConfigIO {
 	clone := ConfigIO{
 		ID:      io.ID,
@@ -47,6 +64,7 @@ type Config struct {
 	LimitCPU       float64    `json:"limit_cpu_usage"`       // percent
 	LimitMemory    uint64     `json:"limit_memory_bytes"`    // bytes
 	LimitWaitFor   uint64     `json:"limit_waitfor_seconds"` // seconds
+	WebRTC         ConfigWebRTC `json:"webrtc"`
 }
 
 func (config *Config) Clone() *Config {
@@ -61,6 +79,7 @@ func (config *Config) Clone() *Config {
 		LimitCPU:       config.LimitCPU,
 		LimitMemory:    config.LimitMemory,
 		LimitWaitFor:   config.LimitWaitFor,
+		WebRTC:         config.WebRTC.Clone(),
 	}
 
 	clone.Input = make([]ConfigIO, len(config.Input))