feat(server): INGEST_WING_RESOLVE=1 wires the wing resolver into the watcher (#205 S3)

Off by default (retired layout unchanged). On: eligibility from
classification.yaml, local ingest LLM as classifier, BM25 as cross-check,
INGEST_WING_THRESHOLD (default 0.9, rejected outside [0,1]). Build failure
is fatal when explicitly enabled.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

ingestion/cmd/server/main_test.go

@@ -76,3 +76,23 @@ func TestAlertingWarnings(t *testing.T) {
 		})
 	}
 }
+
+func TestEnvFloat(t *testing.T) {
+	tests := []struct {
+		name string
+		set  string
+		want float64
+	}{
+		{"unset falls back", "", 0.9},
+		{"valid value", "0.75", 0.75},
+		{"garbage falls back rather than becoming 0", "high", 0.9},
+		{"out of range is rejected, not clamped silently into auto-placing everything", "-1", 0.9},
+		{"above one is rejected", "1.5", 0.9},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Setenv("TEST_ENV_FLOAT", tt.set)
+			assert.InDelta(t, tt.want, envFloat("TEST_ENV_FLOAT", 0.9), 1e-9)
+		})
+	}
+}