chore: rebrand ClubManager -> RosterChief, add lucide icons

The clubmanager.app domain was taken, so the platform is now RosterChief
(rosterchief.app). Renames the Django project package clubmanager/ ->
rosterchief/ (git tracks it as a move, so history follows), every
`from rosterchief.base import ...`, the settings/wsgi/asgi module paths,
env vars (ROSTERCHIEF_BASE_DOMAIN / ROSTERCHIEF_RP_NAME), the MFA adapter
(RosterChiefMFAAdapter), brand text, and the docs.

Two things were deliberately NOT swept:
- club.models.ClubManager stays: it is the Django manager *for Club*, not the
  brand. A blind rename would have silently broken it.
- Migrations are untouched (history is not rewritten). The only reference was a
  cosmetic help_text, so a normal AlterField migration carries the new domain.

Note the WebAuthn RP ID is the base domain, so moving to rosterchief.app
cryptographically invalidates any passkey enrolled under the old one; they
cannot be migrated and must be re-enrolled. Nothing is in production, so the
real cost is zero.

Add django-lucide (from bsiebens/lucide) for icons: the theme toggle now swaps
sun/moon against the effective theme, and the control panel gets icons on its
tabs, actions and stat groups. Its classifiers stop at Django 5.0, but that is
stale metadata — verified rendering on Django 6 / Python 3.14.

Also add formbuilder, shop and controlpanel to ruff's known-first-party list,
which had drifted behind the apps that landed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.env.example

@@ -12,26 +12,26 @@ DJANGO_ALLOWED_HOSTS=.localhost,127.0.0.1,[::1]
 
 # Multi-tenancy: subdomains of this base domain resolve to a club by slug,
 # e.g. http://ajax-united.localhost:8000/ -> club with slug "ajax-united".
-# In production set this to your real base domain (e.g. clubmanager.app).
-CLUBMANAGER_BASE_DOMAIN=localhost
+# In production set this to your real base domain (e.g. rosterchief.app).
+ROSTERCHIEF_BASE_DOMAIN=localhost
 
-# Two-factor auth. CLUBMANAGER_BASE_DOMAIN doubles as the WebAuthn Relying Party
+# Two-factor auth. ROSTERCHIEF_BASE_DOMAIN doubles as the WebAuthn Relying Party
 # ID, so ONE passkey works across every club subdomain. Change it and existing
 # passkeys stop validating -- they are cryptographically bound to that domain.
-# CLUBMANAGER_RP_NAME is what the browser shows during a passkey prompt.
-# CLUBMANAGER_RP_NAME=ClubManager
+# ROSTERCHIEF_RP_NAME is what the browser shows during a passkey prompt.
+# ROSTERCHIEF_RP_NAME=RosterChief
 
 # Sessions are shared across club subdomains (log in once, all clubs). Derived
-# from CLUBMANAGER_BASE_DOMAIN in production; left host-only on localhost
+# from ROSTERCHIEF_BASE_DOMAIN in production; left host-only on localhost
 # because browsers reject a Domain attribute there. Override if needed.
-# DJANGO_SESSION_COOKIE_DOMAIN=.clubmanager.app
-# DJANGO_CSRF_COOKIE_DOMAIN=.clubmanager.app
+# DJANGO_SESSION_COOKIE_DOMAIN=.rosterchief.app
+# DJANGO_CSRF_COOKIE_DOMAIN=.rosterchief.app
 
 # Optional. Defaults to sqlite:///db.sqlite3 for dev; point at Postgres in prod.
-# DJANGO_DATABASE_URL=postgres://user:pass@localhost:5432/clubmanager
+# DJANGO_DATABASE_URL=postgres://user:pass@localhost:5432/rosterchief
 
 # Optional. CSRF trusted origins (needed for subdomains in prod), comma-separated.
-# DJANGO_CSRF_TRUSTED_ORIGINS=https://*.clubmanager.app
+# DJANGO_CSRF_TRUSTED_ORIGINS=https://*.rosterchief.app
 
 # Optional.
 # DJANGO_TIME_ZONE=Europe/Brussels