fix: update demo URL from groombook.farh.net to demo.groombook.dev

Updated UAT_PLAYBOOK.md §2 per QA review (GRO-1819):
- Test environment URL: groombook.farh.net → demo.groombook.dev
- TC-2.1 expected result: groombook.farh.net → demo.groombook.dev
- Added TC-2.3: mobile-groomers.html 'Try the Live Demo' CTA

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

UAT_PLAYBOOK.md

@@ -1,7 +1,7 @@
 # UAT Playbook: GroomBook Site
 
 ## Test Environment
-- **URL:** https://groombook.farh.net (demo)
+- **URL:** https://demo.groombook.dev (demo)
 - **Repository:** https://git.farh.net/groombook/groombook.dev
 - **Last Updated:** 2026-05-26
 
@@ -83,7 +83,7 @@ Verify homepage copy aligns with Path C strategy (solo/small operator focus) wit
 ### TC-2.1: CTA Buttons
 | Step | Action | Expected Result |
 |------|--------|-----------------|
-| 1 | Click "Try the Demo" button | Navigates to https://groombook.farh.net |
+| 1 | Click "Try the Demo" button | Navigates to https://demo.groombook.dev |
 | 2 | Click "View on GitHub" button | Navigates to https://github.com/groombook/groombook |
 
 ### TC-2.2: Badge Display
@@ -91,6 +91,13 @@ Verify homepage copy aligns with Path C strategy (solo/small operator focus) wit
 |------|--------|-----------------|
 | 1 | Locate hero badge | Displays: "🎉 100% Open Source — AGPL-3.0 License" |
 
+### TC-2.3: Mobile Groomers "Try the Live Demo" CTA
+| Step | Action | Expected Result |
+|------|--------|-----------------|
+| 1 | Navigate to mobile-groomers.html | Page loads without errors |
+| 2 | Locate "Try the Live Demo" button | Button is visible with correct styling (green background) |
+| 3 | Click "Try the Live Demo" button | Navigates to https://demo.groombook.dev |
+
 ---
 
 ## 3. Self-Booking CTA (GRO-1791)