Let the admin choose one of eight colour profiles

Indigo (the default), Blue, Teal, Green, Amber, Rose and Violet in the
Vibrant style and Graphite in the Neutral style are generated from
config into the stylesheet. Admin settings opens with a colour profile
card: a swatch previews the profile on the page, and Save Settings
stores it as color_profile, which AppServiceProvider hands to the
package's resolver, so every page, mail and error page wears it. An
unknown profile is refused, and a saved one that disappears falls back
to indigo.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V9NnLxnPp8vaaurb3Z1MFy

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- Eight colour profiles — Indigo (the default), Blue, Teal, Green, Amber, Rose, Violet and Graphite. An admin picks one in Admin settings, previews it on the page, and after saving every page, mail and error page uses it; light and dark stay each visitor's own choice.
 - The share created page offers the link as a QR code: "Show QR code" opens it in a dialog (full screen on a phone) and "Download" saves it as a PNG. For a password-protected share the dialog reminds that recipients also need the password; the code holds only the link.
 - A "Share…" button on the same page opens the device's share sheet with the link, where the browser has one (mostly phones and Safari).