Fix saving personal info on the Admin User page

[ardalis]

Why

Editing a new member's name and email on /Admin/User?userId=... failed with a raw JSON 400 instead of saving:

{"UserId":["The userId field is required."],"InvalidUserId":["Bad Data"],
 "UserPersonalUpdateModel.City":["The City field is required."], ... ,
 "UserPersonalUpdateModel.LastName":["The LastName field is required."]}

Root causes

1. Blank userId. The Personal and Links forms posted UserPersonalUpdateModel.UserId / UserLinksUpdateModel.UserId. Those are only set after OnGetAsync loads the member. That happens after the Stripe invoice search, inside a catch-all that swallows exceptions. If anything earlier fails, the page still renders with an empty hidden userId and every save fails.
2. Address fields are [Required]. New members have no shipping address, so an admin couldn't save a name or email change without inventing an address.
3. BadRequest(ModelState) turned any validation error into raw JSON.

Changes (Admin User page only)

• Adds a UserId page property set from the route at the start of OnGetAsync, and uses it for the Personal and Links hidden fields.
• Wraps the Stripe invoice lookup in its own try/catch with logging, so a Stripe failure doesn't stop the rest of the page from loading.
• OnPostUpdatePersonalInfoAsync:
  • If every shipping address field is blank, drops the address validation errors and leaves the member's shipping address unchanged. Once any address field is filled in, the existing required rules still apply.
  • On a validation failure, reloads the page, keeps the admin's submitted values, and shows inline errors instead of returning a 400 with JSON.
  • A missing member record is shown as an error on the page instead of throwing MemberNotFoundException.
• Adds a validation summary to the Personal card for errors that aren't tied to a field.

UserPersonalUpdateModel itself is unchanged, so validation on members' own My Profile → Personal page is unaffected. That's the difference from draft #1423, which this supersedes.

LastName is still required. Members with a single name will need something entered there. That's now shown as an inline error rather than a 400.

Testing

• dotnet build DevBetterWeb.slnx succeeds.
• DevBetterWeb.Tests: 104/104 pass. 4 new tests for OnPostUpdatePersonalInfoAsync:
  • saves name and email with no shipping address
  • redisplays the form with submitted values when the address is partial
  • redisplays the form instead of returning a 400 when LastName is missing
  • shows an error when there's no member record
• Codex review was not run. The change was self-reviewed.

🤖 Generated with Claude Code