docs(README): add Quick Start section — plugin recommended, CLI second

Mirror the hyperframes README pattern: surface the install paths up front
with the Claude Code plugin as the recommended option (bundles MCP wiring
+ adds /walk-app), standalone CLI as the no-editor alternative, and a
one-line pointer to the MCP server for Cursor/Cline/Goose users.

The detailed Usage section is unchanged — it remains the reference. This
just gives readers a scannable on-ramp before they hit Why this exists.

Author: dadachi

README.md

@@ -21,6 +21,41 @@ npx nativeapptemplate-agent "a walk-in clinic queue for small veterinary practic
 
 ---
 
+## Quick Start
+
+### Option 1: Claude Code plugin (recommended)
+
+Install the plugin once, then drive the agent with two slash commands — `/nativeapptemplate-agent:generate-app` (generate → validate → explain) and `/nativeapptemplate-agent:walk-app` (launch the app on a simulator/emulator and walk its UI via `mobile-mcp`, screenshots inline).
+
+```bash
+/plugin marketplace add nativeapptemplate/nativeapptemplate-agent
+/plugin install nativeapptemplate-agent@nativeapptemplate
+```
+
+Then in Claude Code:
+
+```
+/nativeapptemplate-agent:generate-app a walk-in clinic queue for small veterinary practices. project name is VetClinic.
+```
+
+Or load it locally without the marketplace: `claude --plugin-dir ./plugin`. See [`plugin/README.md`](./plugin/README.md) for the reference card, and the [A-to-Z plugin guide](./docs/PLUGIN-GUIDE.md) for a full walkthrough.
+
+### Option 2: Standalone CLI
+
+No editor required — runs anywhere Node 22+ is installed.
+
+```bash
+npx nativeapptemplate-agent "a walk-in clinic queue for small veterinary practices" --project-name="VetClinic"
+```
+
+Generated output appears under `./out/<slug>/`. See [Usage](#usage) for rename overrides and report flags.
+
+> **Pass a project name.** `--project-name` (or "project name is …" in the plugin) pins the Pascal project name, output slug (`out/vet-clinic/`), Xcode scheme, and display name across all three platforms. Omit it and the planner picks one — fine for one-off exploration, but it'll differ across re-runs.
+
+> Using Cursor, Cline, Goose, or another MCP-capable editor? The generator also ships as an MCP server: `npx -y -p nativeapptemplate-agent nativeapptemplate-agent-mcp` exposes a `generate_app` tool you can wire into your editor's MCP config.
+
+---
+
 ## Why this exists
 
 Most "AI builds an app" tools stop at a single web frontend. The real pain for anyone shipping a mobile product is that the *same* domain has to be implemented three times — multi-tenant Rails API, native iOS, native Android — each with its own idioms, and keeping them consistent is where weeks disappear.