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/store.go

@@ -0,0 +1,111 @@
+package controllogic
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+)
+
+const definitionsFile = "controllogic.json"
+
+// ErrNotFound is returned when a graph id does not exist.
+var ErrNotFound = errors.New("control logic graph not found")
+
+// Store persists control-logic graphs as a single JSON file in the storage dir.
+// Writes are atomic (tmp file + rename); all access is mutex-guarded.
+type Store struct {
+	mu    sync.RWMutex
+	path  string
+	items map[string]Graph
+}
+
+// NewStore opens (or initialises) the control-logic store under storageDir.
+func NewStore(storageDir string) (*Store, error) {
+	s := &Store{
+		path:  filepath.Join(storageDir, definitionsFile),
+		items: map[string]Graph{},
+	}
+	if err := s.load(); err != nil {
+		return nil, err
+	}
+	return s, nil
+}
+
+func (s *Store) load() error {
+	data, err := os.ReadFile(s.path)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	var graphs []Graph
+	if err := json.Unmarshal(data, &graphs); err != nil {
+		return fmt.Errorf("parse %s: %w", s.path, err)
+	}
+	for _, g := range graphs {
+		s.items[g.ID] = g
+	}
+	return nil
+}
+
+// saveLocked writes the current set atomically. Caller must hold s.mu.
+func (s *Store) saveLocked() error {
+	graphs := make([]Graph, 0, len(s.items))
+	for _, g := range s.items {
+		graphs = append(graphs, g)
+	}
+	data, err := json.MarshalIndent(graphs, "", "  ")
+	if err != nil {
+		return err
+	}
+	tmp := s.path + ".tmp"
+	if err := os.WriteFile(tmp, data, 0o644); err != nil {
+		return err
+	}
+	return os.Rename(tmp, s.path)
+}
+
+// List returns all graphs.
+func (s *Store) List() []Graph {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	out := make([]Graph, 0, len(s.items))
+	for _, g := range s.items {
+		out = append(out, g)
+	}
+	return out
+}
+
+// Get returns a single graph by id.
+func (s *Store) Get(id string) (Graph, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	g, ok := s.items[id]
+	if !ok {
+		return Graph{}, ErrNotFound
+	}
+	return g, nil
+}
+
+// Save inserts or replaces a graph and persists the store.
+func (s *Store) Save(g Graph) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.items[g.ID] = g
+	return s.saveLocked()
+}
+
+// Delete removes a graph by id.
+func (s *Store) Delete(id string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if _, ok := s.items[id]; !ok {
+		return ErrNotFound
+	}
+	delete(s.items, id)
+	return s.saveLocked()
+}