Support: add a feedback email, rebrand from Donate, tighten privacy copy

src/app/feedback.ts

@@ -0,0 +1,18 @@
+/**
+ * Project feedback channel.
+ *
+ * There is no server and no tracker (see the About modal — no telemetry of any
+ * kind); feedback is a plain email the user composes and sends from their own
+ * client. The address is a Cloudflare Email Routing alias that forwards to the
+ * author, so it can be retired without exposing or churning a personal inbox.
+ *
+ * Shared by the Support modal and the About modal — a contact address is worth
+ * a single source of truth so the two surfaces can't drift.
+ */
+export const FEEDBACK_EMAIL = 'feedback@astrolabe-viz.com';
+
+/** A `mailto:` href prefilled with a version-stamped subject, to ease triage. */
+export function feedbackMailtoHref(): string {
+  const subject = encodeURIComponent(`Astrolabe v${__APP_VERSION__} — feedback`);
+  return `mailto:${FEEDBACK_EMAIL}?subject=${subject}`;
+}