feat(render): default JSON-model renderer + bright-white values (v1.4.0)

Render(v) treats JSON as the model: in -json mode it prints v as JSON;
otherwise it paints it as text — object scalars on one line as key=value
(keys blue, values bright white: a structural key/value distinction, not
semantic color), nested objects indented, arrays one block per element,
field order preserved via an order-keeping JSON decode. EmitJSON(v) is
the JSON-only arm for commands that paint their own text. Operates on
JSON only, so core stays protobuf-free (NFR-4).

Adds White to the palette. The example gains an `inspect` command
demoing Render (text vs -json). design.md FR-4.5/4.6 document the
renderer and the "JSON is always the full record; synopsis-vs-detail is
text-only" principle.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

example/main.go

@@ -177,6 +177,25 @@ func runWatch(ctx context.Context, _ inventory, _ []string) error {
 	return nil
 }
 
+// runInspect demonstrates the default renderer: it builds one value (the model)
+// and hands it to cli.Render, which prints it as JSON under -json or as painted
+// text (blue keys, bright-white values, nested objects indented) otherwise — no
+// per-command text code.
+func runInspect(_ context.Context, inv inventory, _ []string) error {
+	type host struct {
+		Name     string   `json:"name"`
+		Services []string `json:"services"`
+	}
+	f := struct {
+		Count int    `json:"count"`
+		Hosts []host `json:"hosts"`
+	}{Count: len(inv.servers)}
+	for _, n := range inv.names() {
+		f.Hosts = append(f.Hosts, host{Name: n, Services: inv.servers[n]})
+	}
+	return cli.Render(f)
+}
+
 func runQuit(context.Context, inventory, []string) error { return cli.ErrQuit }
 
 // buildTree is the single source of truth for the command set, built with the
@@ -192,6 +211,7 @@ func buildTree() *cli.Node[inventory] {
 		b.Dir("ping", "ping a server",
 			b.Slot("<name>", "ping this server", dynServers, runPing)),
 		b.Cmd("watch", "stream a few events (any key stops it)", runWatch),
+		b.Cmd("inspect", "render the fleet via the default renderer (try -json / -color)", runInspect),
 		b.Cmd("colors", "show the ANSI color palette", runColors),
 		b.Cmd("quit", "exit the shell", runQuit),
 		b.Cmd("exit", "exit the shell", runQuit),