docs: bring the Quick Start guide (incl. Windows prebuilt steps) to main

main shipped v1.0.0 with prebuilt Windows binaries but no docs on main
explaining what the .exe is or how to run it (#450) — the quickstart lived
only on dev. Bring docs/quickstart.md to main and add a Windows-prebuilt
pointer to the README's Get started section, so users on the default branch
find the steps. Docs-only.

Refs #450

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -151,6 +151,15 @@ scale-granularity/rotation ablations live in
 
 ## Get started
 
+> **New here, or on Windows?** The [Quick Start guide](docs/quickstart.md) walks
+> through install → build → model → first chat step by step for Linux, Windows,
+> and macOS. On **Windows** you don't even need to build: download the
+> `colibri-<version>-windows-x86_64.zip` from
+> [Releases](https://github.com/JustVugg/colibri/releases), unzip it, rename
+> `colibri-*-windows-x86_64.exe` → `glm.exe`, install
+> [Python 3](https://www.python.org/downloads/), and run `coli chat` — full
+> details in the [Windows section](docs/quickstart.md#windows).
+
 ### 1. Get the model
 
 A pre-converted **GLM-5.2 int4** container is on Hugging Face — **use the