support: feedback defaults to anonymous, reveals email when off
- Default #feedback-anonymous to checked; unchecking reveals an email input plus a "we never use your email for anything beyond replying" privacy-policy link (https://solpbc.org/privacy).
- Thread optional user_email through support_feedback → support_create → PortalClient.create_ticket. Route normalizes empty/whitespace email to omitted; anonymous submissions always strip user_email server-side (defense in depth).
- Tests cover the four route boundary cases: anonymous-no-email, identified-with-email, anonymous-drops-smuggled-email, identified-empty-email-omits-kwarg.