feat: public profile page + richer hover card with "See full profile"

- New /users/{id} page renders a user's full profile from the card endpoint:
  avatar, roles, full bio, contact (location/phone), links and custom detail
  fields (internal extra keys hidden; link schemes sanitized).
- The hover user-card now shows a longer bio, phone, up to 3 links, and a
  "See full profile →" button linking to /users/{id}.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/templates/public-profile.html

@@ -0,0 +1,4 @@
+{{define "content"}}
+<div class="error-box" id="error" role="alert"></div>
+<div id="profile-root" data-user-id="{{.Data.UserID}}"></div>
+{{end}}