Add control logic engine, panel logic dialogs, logic-edit restriction

Introduce server-side control-logic flow graphs (cron/alarm triggers,
Lua blocks) with CRUD endpoints, panel-logic lifecycle triggers and
user-interaction dialog nodes, and a synthetic node-graph editor.

Add an optional logic-editor allowlist (server.logic_editors) gating who
may add/edit panel logic and control logic, surfaced via /api/v1/me and
enforced in the API; hide logic affordances in the UI accordingly.

Update README, example config, and functional/technical specs to cover
all current features (plot panels, panel/control logic, local variables,
access control) and refresh the in-app manual and contextual help.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/controllogic/expr_test.go

@@ -0,0 +1,86 @@
+package controllogic
+
+import (
+	"math"
+	"testing"
+)
+
+func TestEvalExpr(t *testing.T) {
+	resolve := func(ds, name string) float64 {
+		switch {
+		case ds == "stub" && name == "x":
+			return 10
+		case ds == "local" && name == "y":
+			return 3
+		case ds == "sys" && name == "dt":
+			return 0.5
+		}
+		return math.NaN()
+	}
+	cases := []struct {
+		expr string
+		want float64
+	}{
+		{"1 + 2 * 3", 7},
+		{"(1 + 2) * 3", 9},
+		{"10 % 3", 1},
+		{"{stub:x} + y", 13},
+		{"{stub:x} > 5 ? 1 : 0", 1},
+		{"min(4, 2, 8)", 2},
+		{"max(4, 2, 8)", 8},
+		{"abs(-5)", 5},
+		{"sqrt(16)", 4},
+		{"2 < 3 && 3 < 4", 1},
+		{"!0", 1},
+		{"-{stub:x}", -10},
+		{"{sys:dt} * 2", 1},
+		{"true + false", 1},
+	}
+	for _, c := range cases {
+		got := EvalExpr(c.expr, resolve)
+		if math.Abs(got-c.want) > 1e-9 {
+			t.Errorf("EvalExpr(%q) = %v, want %v", c.expr, got, c.want)
+		}
+	}
+}
+
+func TestEvalExprErrors(t *testing.T) {
+	r := func(ds, name string) float64 { return 0 }
+	for _, bad := range []string{"1 +", "(1", "1 2", "{unterminated"} {
+		if v := EvalExpr(bad, r); !math.IsNaN(v) {
+			t.Errorf("EvalExpr(%q) = %v, want NaN", bad, v)
+		}
+	}
+}
+
+func TestCollectRefs(t *testing.T) {
+	refs := CollectRefs("{stub:x} + y + {epics:MY:PV} * z")
+	got := map[string]bool{}
+	for _, r := range refs {
+		got[r.DS+":"+r.Name] = true
+	}
+	for _, want := range []string{"stub:x", "local:y", "epics:MY:PV", "local:z"} {
+		if !got[want] {
+			t.Errorf("CollectRefs missing %q (got %v)", want, got)
+		}
+	}
+}
+
+func TestCheckExpr(t *testing.T) {
+	if msg := CheckExpr("1 + 2"); msg != "" {
+		t.Errorf("CheckExpr valid returned %q", msg)
+	}
+	if msg := CheckExpr("1 +"); msg == "" {
+		t.Errorf("CheckExpr invalid returned empty")
+	}
+	if msg := CheckExpr(""); msg != "" {
+		t.Errorf("CheckExpr empty returned %q", msg)
+	}
+}
+
+func TestEpicsRefSplitFirstColon(t *testing.T) {
+	refs := CollectRefs("{epics:SR:BPM:01:X}")
+	if len(refs) != 1 || refs[0].DS != "epics" || refs[0].Name != "SR:BPM:01:X" {
+		t.Errorf("got %+v, want epics / SR:BPM:01:X", refs)
+	}
+}