<!-- Describe your changes in detail -->
Whenever a user signs up on the dashboard, they receieve a welcome email , welcoming them to the community. I have changed the text and formatting of the email.

There is a welcome_to_community.html file which is sent as the email body whenever a user signs up. This PR modifies this email to be a pure text email with links .

This is how the new email will look.
To implement this **search_filter** feature, you'll need to modify these architectural layers:


**1. Other**
   - `crates/router/src/services/email/assets/welcome_to_community.html`

**Code Patterns Applied:**
- Extend existing types with new fields (3 changes)
{"pr_number": 7982, "pr_title": "refactor(users): Change welcome email text and formatting", "merged_at": "2025-05-15T10:46:49Z", "intent": {"feature_type": "search_filter", "action": "add_feature", "entities": ["user"]}, "hierarchy": {"other": ["crates/router/src/services/email/assets/welcome_to_community.html"]}, "change_types": {"fields_added": 3}, "has_identifier_data": false, "commits_matched": 0, "match_method": "none"}