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/access/access.go

@@ -56,19 +56,29 @@ func ParseLevel(s string) Level {
 // Policy holds the resolved global access configuration. It is immutable after
 // construction and safe for concurrent use.
 type Policy struct {
-	defaultUser string
-	blacklist   map[string]Level    // user → downgraded level
-	userGroups  map[string][]string // user → groups they belong to
-	groupNames  []string            // all configured group names (sorted)
+	defaultUser  string
+	blacklist    map[string]Level    // user → downgraded level
+	userGroups   map[string][]string // user → groups they belong to
+	groupNames   []string            // all configured group names (sorted)
+	logicEditors map[string]bool     // users + group names allowed to edit logic
 }
 
 // New builds a Policy. blacklist maps a username to a config level string;
-// groups maps a group name to its member usernames.
-func New(defaultUser string, blacklist map[string]string, groups map[string][]string) *Policy {
+// groups maps a group name to its member usernames. logicEditors optionally
+// restricts who may edit panel/control logic (usernames or group names); empty
+// means no restriction.
+func New(defaultUser string, blacklist map[string]string, groups map[string][]string, logicEditors []string) *Policy {
 	p := &Policy{
-		defaultUser: strings.TrimSpace(defaultUser),
-		blacklist:   make(map[string]Level),
-		userGroups:  make(map[string][]string),
+		defaultUser:  strings.TrimSpace(defaultUser),
+		blacklist:    make(map[string]Level),
+		userGroups:   make(map[string][]string),
+		logicEditors: make(map[string]bool),
+	}
+	for _, e := range logicEditors {
+		e = strings.TrimSpace(e)
+		if e != "" {
+			p.logicEditors[e] = true
+		}
 	}
 	for user, lvl := range blacklist {
 		u := strings.TrimSpace(user)
@@ -126,6 +136,35 @@ func (p *Policy) Level(user string) Level {
 	return LevelWrite
 }
 
+// LogicRestricted reports whether a logic-editor allowlist is configured. When
+// false, any write-capable user may edit panel/control logic.
+func (p *Policy) LogicRestricted() bool {
+	return len(p.logicEditors) > 0
+}
+
+// CanEditLogic reports whether a user may add or edit panel logic and
+// server-side control logic. When no allowlist is configured everyone with
+// write access qualifies; otherwise the user (or one of their groups) must be
+// listed. Anonymous/trusted-LAN callers (user=="") are always permitted.
+func (p *Policy) CanEditLogic(user string) bool {
+	user = strings.TrimSpace(user)
+	if user == "" {
+		return true
+	}
+	if !p.LogicRestricted() {
+		return true
+	}
+	if p.logicEditors[user] {
+		return true
+	}
+	for _, g := range p.userGroups[user] {
+		if p.logicEditors[g] {
+			return true
+		}
+	}
+	return false
+}
+
 // GroupsOf returns a copy of the groups a user belongs to.
 func (p *Policy) GroupsOf(user string) []string {
 	src := p.userGroups[strings.TrimSpace(user)]