Add a one-line quickstart and a demo recording script to the README

Put a zero-install pipx/uvx one-liner above the fold so a visitor can try a scan
in seconds, and pull the output preview up next to it. Add assets/demo.tape so
the static preview can be replaced with an animated VHS demo GIF.

Author: sanmaxdev

README.md

@@ -9,6 +9,18 @@
 
 </div>
 
+> **Scan any domain you are authorised to assess in one line. Nothing to install:**
+
+```bash
+pipx run sentineldeck scan example.com        # or:  uvx sentineldeck scan example.com
+```
+
+Prefer a permanent install? `pip install -U sentineldeck`, then `sentineldeck scan example.com`.
+
+<p align="center">
+  <img src="assets/cli.svg" alt="SentinelDeck command-line output" width="720">
+</p>
+
 <table>
   <tr>
     <td><b>Testing</b></td>
@@ -60,10 +72,6 @@ It is built for the people who need that picture fast: an agency qualifying a
 prospect, a consultant producing a client report, or a small team checking its
 own footprint.
 
-<p align="center">
-  <img src="assets/cli.svg" alt="SentinelDeck command-line home screen" width="720">
-</p>
-
 ## Contents
 
 - [Features](#features)

assets/demo.tape

@@ -0,0 +1,34 @@
+# SentinelDeck animated demo.
+#
+# Generate the GIF with charmbracelet/vhs (https://github.com/charmbracelet/vhs):
+#
+#   vhs assets/demo.tape        ->  writes assets/demo.gif
+#
+# Then swap the static assets/cli.svg in README.md for assets/demo.gif.
+# Requires sentineldeck on PATH (pip install -e . or pipx install sentineldeck)
+# and network access for the live scan.
+
+Output assets/demo.gif
+
+Set Shell "bash"
+Set FontSize 16
+Set Width 1200
+Set Height 760
+Set Padding 24
+Set Theme "Catppuccin Mocha"
+Set TypingSpeed 60ms
+
+# 1. The branded home screen (instant, no network).
+Type "sentineldeck"
+Enter
+Sleep 3s
+
+# 2. A real passive scan turning a domain into a grade and findings.
+Type "sentineldeck scan example.com"
+Enter
+Sleep 8s
+
+# 3. Render a client-ready HTML report.
+Type "sentineldeck scan example.com --html report.html"
+Enter
+Sleep 5s