Move email previews onto the Club identity page; add PDF previews

Three top-level tabs (Identity/Email/PDF) replace the standalone
Settings > Email previews page and the small mock that used to live
inside the Identity tab's own Email sub-tab. Email and PDF now show
every real branded email/generated PDF this club can send, rendered
with sample data via a shared _document_preview_card.html partial
(email cards keep the HTML/plain-text toggle; PDF cards -- the
underlying HTML WeasyPrint would turn into a PDF, shown directly
rather than round-tripping through WeasyPrint -- don't need one).

Added a password-reset email preview (previously missing from the
audit -- it's allauth's own send path, not one of this app's, so it
didn't show up in the earlier grep for EmailMultiAlternatives/.send()
calls). Dropped parent-claim-approved: not directly used right now.

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

management/context_processors.py

@@ -127,7 +127,6 @@ _NAV_SECTIONS = {
     "form_list": "form_list",
     "submission_list": "form_list",
     "club_settings": "club_settings",
-    "email_preview_list": "email_preview_list",
     "onboarding_requirement_list": "onboarding_requirement_list",
     "onboarding_requirement_create": "onboarding_requirement_list",
     "onboarding_requirement_update": "onboarding_requirement_list",
@@ -173,7 +172,6 @@ _TOP_SECTION = {
     "invoice_list": "finance",
     "form_list": "settings",
     "club_settings": "settings",
-    "email_preview_list": "settings",
     "onboarding_requirement_list": "settings",
     "role_list": "settings",
     "position_list": "settings",