feat: add chat

internal/model/social.go

@@ -183,6 +183,15 @@ type RelationshipState struct {
 	RequestsYou     bool `json:"requests_you"`
 	Blocked         bool `json:"blocked"`
 	BlockedBy       bool `json:"blocked_by"`
+	// CanMessage reports whether the viewer may START a conversation with this
+	// profile, given the target's "who can message you" setting and any block.
+	// It lets the UI decide whether to offer a Message button rather than
+	// offering one that fails on tap.
+	CanMessage bool `json:"can_message"`
+	// MessageRestriction names the target's rule when CanMessage is false, so
+	// the UI can explain instead of silently hiding the button. Empty when
+	// messaging is allowed, or "blocked" when a block is the reason.
+	MessageRestriction string `json:"message_restriction,omitempty"`
 }
 
 // Follow is one row of the follows table — a directed, request-based