feat: profile bio

internal/model/user.go

@@ -52,6 +52,13 @@ type User struct {
 	// public profile exposes only the derived `is_direct_disciple` flag.
 	DiscipleID *string `json:"-"`
 
+	// Bio is a short self-introduction (max 200 characters, enforced in the
+	// service by rune count) shown on the profile header. Stored as PLAIN
+	// TEXT — `@handle` mentions are kept verbatim and linkified by the
+	// frontend at render time, so it must never be injected as HTML.
+	// nil when unset.
+	Bio *string `json:"bio"`
+
 	// --- Devotional profile (user-editable) ---
 	// Gender is a free-but-constrained string ("male"|"female"|"other"),
 	// nil when unspecified.