Improve the LFX Mentorship Proposal form - nitpicks / requirements

### 1. why give program name twice

### 2. what is school enrollment verification (an explanation would be good)

### 3. upstream issue url - should also in the issue the bot should update it to render the issue as a dropdown (more like iframe / dropdown) so we could see whats the issue is about without clicking and going through the link. (nitpick)

### 4. search on the project selection would be good (nitpick)

### 5. LF username is confusing and hard to find. given that LF doesnt follow the norm of how other socials actually works with the username. by showing them in the url like bsky.app/profile/bupd.xyz - this doesnt happen in lfx - people need to find what their username but its actually hidden and only place to get that is from `copy public profile url`. which is kinda hassle to get to this page.

### 6. pasting mentor profile URL/LF username should work in the mentors field (requirement)

No files or tests are named. Start by locating the LFX Mentorship Proposal form and its project and mentor selectors, then compare the current behavior with the six numbered requirements; done means the duplicate field is removed or clarified, issue details are rendered, project search works, LF usernames are discoverable, and mentor URLs or usernames are accepted.

Written by the indexing model from the issue text.