Machine/endpoint selector doesn't persist selection on /new page #315

Bug Description

When attempting to create a new session at https://app.happy.engineering/new, the machine/endpoint selector does not persist the selected value. This makes it impossible to launch sessions from any machine other than the default.

Steps to Reproduce

1. Navigate to https://app.happy.engineering/new
2. Click on the machine/endpoint dropdown (e.g., shows Example-DevVM01)
3. Select a different machine from the list (e.g., Example-DevVM02 or Example-DevVM03)
4. Observe that the selection reverts back to the original machine
5. Attempting to create a session always uses the default machine, not the selected one

Expected Behavior

• Machine selection should persist when changed when trying to create a new session
• The selected machine should remain visible in the dropdown
• Creating a session should use the currently selected machine

Actual Behavior

• Machine selection reverts to default immediately after selection
• Cannot create sessions from any machine except the default
• Path input has similar persistence issues

Environment

• Browser: Google Chrome and MS Edge - up to date
• OS: Windows 11
• Multiple machines configured and online:
  • Example-DevVM01 (default)
  • Example-DevVM02
  • Example-DevVM03

Additional Context

This appears to be a state management issue in the frontend where form input changes aren't properly binding to component state. The dropdown shows the options correctly, but the selection change event doesn't update the underlying state.

Impact

This effectively means users who use multiple machines can only create new sessions from one single machine. This combined with the other open bug affecting random processes crashing can make Happy very UNhappy to use.