feat: initial scaffold kanban_cpp v0.1.0

C++ ImGui kanban for steering LLM agents. Six panels (Board, Calendar,
Dashboard, Agent runs, Worktrees, DoD inspector) wired to registry
functions http_request, kpi_card, sparkline, agent_runs_timeline,
dod_evidence_panel. Backend Go on :8403 (independent operations.db from
kanban_web).

backend/flags.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"encoding/json"
+	"net/http"
+	"os"
+
+	"fn-registry/functions/infra"
+)
+
+type FeatureFlag struct {
+	Enabled     bool   `json:"enabled"`
+	Issue       string `json:"issue,omitempty"`
+	Description string `json:"description"`
+	Added       string `json:"added,omitempty"`
+	EnabledAt   string `json:"enabled_at,omitempty"`
+}
+
+type FeatureFlags struct {
+	Flags map[string]FeatureFlag `json:"flags"`
+}
+
+func (f FeatureFlags) Enabled(name string) bool {
+	flag, ok := f.Flags[name]
+	return ok && flag.Enabled
+}
+
+func loadFeatureFlags(path string) (FeatureFlags, error) {
+	b, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return FeatureFlags{Flags: map[string]FeatureFlag{}}, nil
+		}
+		return FeatureFlags{}, err
+	}
+	var f FeatureFlags
+	if err := json.Unmarshal(b, &f); err != nil {
+		return FeatureFlags{}, err
+	}
+	if f.Flags == nil {
+		f.Flags = map[string]FeatureFlag{}
+	}
+	return f, nil
+}
+
+// GET /api/flags → { "<name>": true/false, ... }
+func handleListFlags(flags *FeatureFlags) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		out := make(map[string]bool, len(flags.Flags))
+		for name, fl := range flags.Flags {
+			out[name] = fl.Enabled
+		}
+		infra.HTTPJSONResponse(w, http.StatusOK, out)
+	}
+}