User profiles (title, avatar)

## Parent

[Map: BSR member platform MVP](https://github.com/fkeenv/bsr/issues/1)

## What to build

Add a `user_profiles` table for User Account presentation data — at least optional **title** (e.g. Treasurer) and **avatar**, Twitter-simple. Not a platform role; titles are display-only ([ADR-0017](https://github.com/fkeenv/bsr/blob/main/docs/adr/0017-spatie-platform-roles-with-level-inheritance.md)).

## Acceptance criteria

- [ ] `user_profiles` table related 1:1 to `users`
- [ ] Optional title and avatar fields
- [ ] User can update their own profile basics
- [ ] Feature tests cover create-on-register or lazy create and update

Read docs/adr/0017-spatie-platform-roles-with-level-inheritance.md and inspect the existing users and registration flow first; the issue does not name implementation files. Decide whether profiles are created on registration or lazily, then cover the 1:1 relationship, optional fields, self-update behavior, and the chosen flow with feature tests.

Written by the indexing model from the issue text.