chore: unify dev setup with concurrently

Adds concurrently to start both the Vite frontend and Hono backend simultaneously in one terminal via the `bun run dev` command. Also updates documentation in README.md and CLAUDE.md to reflect the new development workflow.

README.md

@@ -10,7 +10,7 @@ A single-user web app for managing gear collections (bikepacking, sim racing, et
 - Research threads for comparing candidates before buying
 - Image uploads for items and candidates
 
-## Quick Start
+## Quick Start (Docker)
 
 ### Docker Compose (recommended)
 
@@ -81,3 +81,42 @@ docker compose up -d
 ```
 
 Database migrations run automatically on startup.
+
+## Tech Stack
+
+- **Runtime & Package Manager:** [Bun](https://bun.sh)
+- **Frontend:** React 19, Vite, TanStack Router, TanStack Query, Tailwind CSS v4, Zustand
+- **Backend:** Hono, Drizzle ORM, SQLite (`bun:sqlite`)
+
+## Local Development Setup
+
+### Prerequisites
+
+You must have [Bun](https://bun.sh/) installed on your machine. Docker is not required for local development.
+
+### Installation
+
+1. Install all dependencies:
+   ```bash
+   bun install
+   ```
+
+2. Initialize the local SQLite database (`gearbox.db`):
+   ```bash
+   bun run db:push
+   ```
+
+3. Start the development servers:
+   ```bash
+   bun run dev
+   ```
+   This single command will start both the Vite frontend server (port `5173`) and the Hono backend server (port `3000`) concurrently. 
+
+Open [http://localhost:5173](http://localhost:5173) in your browser to view the app.
+
+## Additional Commands
+
+- `bun run build` — Build the production assets into `dist/client/`
+- `bun test` — Run the test suite
+- `bun run lint` — Check formatting and lint rules using Biome
+- `bun run db:generate` — Generate Drizzle migrations after making schema changes