docs: define CPA blue/green brand and refresh package hero

Codify the org node-graph palette and Beta messaging so website, GitHub,
and PyPI surfaces share one identity.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: ulises-jeremias

docs/BRAND.md

@@ -1,6 +1,36 @@
 # Brand
 
-Working identity for CPA (to be refined):
+Canonical visual identity for Create Awesome Python App across GitHub, PyPI, the website, and generated starters.
 
-- Tagline: One command. Any Python stack.
-- Story: choose template → add addons → ship with uv
+## Identity
+
+**Python node-graph** — composition-first scaffolding with a cool blue → green mark (distinct from Create Node App’s cozy amber → teal nest).
+
+| Token   | Value                 | Use                              |
+|---------|-----------------------|----------------------------------|
+| Blue    | `#3b82f6` / `#2563eb` | Primary accent, CTAs, highlights |
+| Green   | `#16a34a` / `#22c55e` | Secondary accent, success, links |
+| Dark bg | `#0f172a`             | Default surfaces                 |
+| Light bg| `#f8fafc`             | Light-mode surfaces              |
+
+Primary gradient: `135deg, #3b82f6 → #2563eb → #16a34a`.
+
+## Messaging
+
+- **Tagline:** One command. Any Python stack.
+- **Story:** choose template → add addons → ship with uv
+- **Status:** Public **Beta** (CLI + catalog + website live)
+- **Audience split:** root README = contributors; package README = PyPI users; website = conversion + catalog
+
+## Source of truth
+
+- Org profile banner: [`Create-Python-App/.github`](https://github.com/Create-Python-App/.github) — `profile/banner.svg`
+- Marketing site: [`Create-Python-App/website`](https://github.com/Create-Python-App/website) — live at [create-awesome-python-app.vercel.app](https://create-awesome-python-app.vercel.app/)
+- Package hero: `packages/create-awesome-python-app/assets/hero.svg`
+
+## Do / don't
+
+- Do keep the node-graph logomark (composition metaphor shared with CNA, different palette)
+- Do prefer uv-first CTAs (`uvx create-awesome-python-app@latest`)
+- Don't reuse CNA amber/teal as the primary CPA palette
+- Don't invent a second logo system outside the node-graph mark