feat: P1-1 handle resource value push via OPCode_notify

Add OPCode_notify handler in go_push_handler top-level switch
(not inside handlePush) to receive resource value updates from
the controller via xce_notify_data_t/schedUpdateResvals.

- Add 8 CGO union accessors for xce_val_t (which, i32, i64,
  u32, u64, fval, str, bool) since CGO cannot access union fields
- Add handleNotifyData() dispatching NotifyData_data_schedUpdateResvals
  events, iterating xce_resval_list_t and calling cResvalToDistribution
- Add cResvalToDistribution in convert.go with 7 separate switch
  cases for Value_u_* union discriminants (no combining i32/i64)
- Add rawResvalData + rawResvalToDistribution pure-Go version
  in convert_pure.go for testability without CGO
- Add 10 TDD tests covering all 7 value types, nil val guard,
  unknown discriminant, and boolean false
- All 42 backend tests passing

src/frontend/apiserver/backend/convert_pure.go

@@ -13,16 +13,16 @@ import (
 const (
 	nTagBits          = 2
 	tagShift          = 62
-	nClusterIDBits   = 6
-	clusterIDShift   = 56
-	nApiserverIDBits = 4
-	apiserverIDShift = 52
-	nTimestampBits   = 32
-	timestampShift   = 20
-	nArrayIdxBits    = 15
-	sequenceHighShift = 15 // mirrors SEQUENCE_HIGH_SHIFT in config.h
-	nSequenceBits    = 30 // mirrors N_SEQUENCE_BITS in config.h
-	tagJobArray      = 0x01 // mirrors TAG_JOB_ARRAY in config.h
+	nClusterIDBits    = 6
+	clusterIDShift    = 56
+	nApiserverIDBits  = 4
+	apiserverIDShift  = 52
+	nTimestampBits    = 32
+	timestampShift    = 20
+	nArrayIdxBits     = 15
+	sequenceHighShift = 15   // mirrors SEQUENCE_HIGH_SHIFT in config.h
+	nSequenceBits     = 30   // mirrors N_SEQUENCE_BITS in config.h
+	tagJobArray       = 0x01 // mirrors TAG_JOB_ARRAY in config.h
 )
 
 // extractBits extracts a bit field from id at the given shift position.
@@ -260,14 +260,70 @@ func rawHostConfigToModel(r rawHostConfigData) *models.HostInfo {
 	}
 }
 
+// rawResvalData mirrors the C xce_resval_t fields used by the Go model.
+// IsDynamic is always true for push-sourced values (controller sends live measurements).
+type rawResvalData struct {
+	name     string
+	host     string
+	valWhich int // mirrors C xce_val_t.which (Value_u_* discriminant)
+	i32      int32
+	i64      int64
+	u32      uint32
+	u64      uint64
+	fval     float64
+	sval     string
+	bval     bool
+	valNil   bool // true when the C xce_val_t* was NULL
+}
+
+// rawResvalToDistribution maps a rawResvalData to a models.ResourceDistributionInfo.
+// Returns nil when valNil is true (C val pointer was NULL) or when valWhich
+// is an unknown discriminant — callers should skip nil results.
+func rawResvalToDistribution(r rawResvalData) *models.ResourceDistributionInfo {
+	rd := &models.ResourceDistributionInfo{
+		ResourceName: r.name,
+		Location:     r.host,
+		IsDynamic:    true, // resource values pushed from workers are always dynamic
+	}
+	if r.valNil {
+		return nil
+	}
+	switch r.valWhich {
+	case 0: // Value_u_ivalue32
+		rd.ValueType = int(models.NUMERIC)
+		rd.NumericValue = float64(r.i32)
+	case 2: // Value_u_ivalue64
+		rd.ValueType = int(models.NUMERIC)
+		rd.NumericValue = float64(r.i64)
+	case 1: // Value_u_uvalue32
+		rd.ValueType = int(models.NUMERIC)
+		rd.NumericValue = float64(r.u32)
+	case 3: // Value_u_uvalue64
+		rd.ValueType = int(models.NUMERIC)
+		rd.NumericValue = float64(r.u64)
+	case 5: // Value_u_fvalue
+		rd.ValueType = int(models.NUMERIC)
+		rd.NumericValue = r.fval
+	case 4: // Value_u_svalue
+		rd.ValueType = int(models.STRING)
+		rd.StringValue = r.sval
+	case 6: // Value_u_bvalue
+		rd.ValueType = int(models.BOOLEAN)
+		rd.BooleanValue = r.bval
+	default:
+		return nil
+	}
+	return rd
+}
+
 // rawClusterData mirrors the C cluster_config_t fields used by the Go model.
 // Only config-sourced fields are included (heartbeat_interval, vcpus, inactive_heartbeat_count).
 // Built-in/sourced fields (Version, Status, ControllerName, etc.) come from LoadBuiltinData
 // and are not part of the config push conversion.
 type rawClusterData struct {
 	name                   string
-	heartbeatInterval     int
-	vcpus                 int
+	heartbeatInterval      int
+	vcpus                  int
 	inactiveHeartbeatCount int
 }