Update missing mailto: in some snaps contact metadata (#872)

### PR Description

#### What is the current state of things and why does it need to change?
The contact fields for some snaps in the `registry.json` file currently
contain email addresses without the `mailto:` prefix. This could cause
inconsistencies or issues where the correct format (with `mailto:`) is
expected.

#### What is the solution your changes offer and how does it work?
This PR updates the `contact` field for the affected snaps to include
the `mailto:` prefix, ensuring all email addresses are in the proper
format for links and interactions. Specifically, three snaps have been
updated:

- **Qtum Snap**: Changed `"[email protected]"` to
`"mailto:[email protected]"`.
- **Aeternity Snap**: Changed `"[email protected]"` to
`"mailto:[email protected]"`.
- **TokenScript Snap**: Changed `"[email protected]"` to
`"mailto:[email protected]"`.

#### Are there any issues or other links reviewers should consult to
understand this pull request better?
No related issues were filed, but these changes are necessary for
consistent contact formatting across snaps.

Co-authored-by: Frederik Bolding <[email protected]>

src/registry.json

@@ -1334,7 +1334,7 @@
         ],
         "category": "interoperability",
         "support": {
-          "contact": "[email protected]",
+          "contact": "mailto:[email protected]",
           "faq": "https://github.com/qtumproject/qtum-extension-wallet?tab=readme-ov-file#qtum-wallet-faq",
           "knowledgeBase": "https://github.com/qtumproject/qtum-extension-wallet?tab=readme-ov-file#qtum-wallet-knowledge-doc"
         },
@@ -2078,7 +2078,7 @@
         ],
         "category": "interoperability",
         "support": {
-          "contact": "[email protected]"
+          "contact": "mailto:[email protected]"
         },
         "sourceCode": "https://github.com/4-point-0/aeternity-snap"
       },
@@ -3612,7 +3612,7 @@
         "support": {
           "knowledgeBase": "https://github.com/TokenScript-Framework/token-kit/blob/main/packages/tapp-snap/README.md",
           "faq": "https://github.com/TokenScript-Framework/token-kit/blob/main/packages/tapp-snap/FAQ.md",
-          "contact": "[email protected]"
+          "contact": "mailto:[email protected]"
         },
         "sourceCode": "https://github.com/TokenScript-Framework/token-kit/tree/main/packages/tapp-snap",
         "screenshots": [