Add a club legal address, used for invoices/referee forms ahead of the home ground

New Club.legal_address/legal_zip_code/legal_city, editable from the
identity page (management:club_settings). Official document headers
(the dues invoice, the referee payment form) previously borrowed the
club's home Location for this -- conflating "where we play" with "our
registered address", which aren't always the same place. New
club.services.invoicing.resolve_document_address(club) picks the club's
own legal address when set, falling back to the home Location exactly as
before when it isn't, so nothing breaks for a club that hasn't set one
yet. Location.is_home now means only what it always should have: telling
a home game from an away one.

Renamed the shared "home_location" template/context variable to
"document_address" on both PDFs to match -- it was never accurate once a
legal address could win instead.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ECGMEwrc2k4D8VQuwjstj9

club/templates/club/dues_invoice_pdf.html

@@ -43,9 +43,9 @@
         <div class="header">
             <div>
                 <h1>{{ club.official_name }}</h1>
-                {% if home_location %}
-                    <div class="muted">{{ home_location.address }}</div>
-                    <div class="muted">{{ home_location.zip_code }} {{ home_location.city }}</div>
+                {% if document_address %}
+                    <div class="muted">{{ document_address.address }}</div>
+                    <div class="muted">{{ document_address.zip_code }} {{ document_address.city }}</div>
                 {% endif %}
                 {% if club.contact_email %}<div class="muted">{{ club.contact_email }}</div>{% endif %}
             </div>