Add a way to add private notes for users on their profile

This is a common feature in other chat applications (like Discord) as a
way to keep track of important information. While there isn't a standard
API for this, we can use account data to store notes.

src/app/qml/UserDetailDialog.qml

@@ -401,5 +401,34 @@ Kirigami.Dialog {
                 color: Kirigami.Theme.disabledTextColor
             }
         }
+
+        Kirigami.Heading {
+            text: i18nc("@title Private note for this user", "Private Note")
+            level: 4
+
+            Layout.topMargin: Kirigami.Units.largeSpacing
+        }
+
+        QQC2.TextArea {
+            id: noteText
+
+            text: root.connection.noteForUser(root.user.id)
+            textFormat: TextEdit.PlainText
+            wrapMode: TextEdit.Wrap
+            placeholderText: i18nc("@info:placeholder", "Only visible to you")
+
+            onTextEdited: editTimer.restart()
+
+            Layout.fillWidth: true
+            Layout.topMargin: Kirigami.Units.smallSpacing
+
+            // Prevent unnecessary edits by waiting 1 second
+            Timer {
+                id: editTimer
+
+                interval: 1000
+                onTriggered: root.connection.setNoteForUser(root.user.id, noteText.text)
+            }
+        }
     }
 }

src/libneochat/neochatconnection.cpp

@@ -619,4 +619,21 @@ bool NeoChatConnection::supportsMatrixSpecVersion(const QString &version)
     return supportedMatrixSpecVersions().contains(version);
 }
 
+QString NeoChatConnection::noteForUser(const QString &userId)
+{
+    const auto object = accountDataJson(QStringLiteral("org.kde.neochat.user_note"));
+    return object[userId].toString();
+}
+
+void NeoChatConnection::setNoteForUser(const QString &userId, const QString &note)
+{
+    auto object = accountDataJson(QStringLiteral("org.kde.neochat.user_note"));
+    if (note.isEmpty()) {
+        object.remove(userId);
+    } else {
+        object[userId] = note;
+    }
+    setAccountData(QStringLiteral("org.kde.neochat.user_note"), object);
+}
+
 #include "moc_neochatconnection.cpp"

src/libneochat/neochatconnection.h

@@ -234,6 +234,16 @@ public:
      */
     Q_INVOKABLE bool supportsMatrixSpecVersion(const QString &version);
 
+    /**
+     * @return The private note for this user, if set.
+     */
+    Q_INVOKABLE QString noteForUser(const QString &userId);
+
+    /**
+     * @brief Sets the private note for this user.
+     */
+    Q_INVOKABLE void setNoteForUser(const QString &userId, const QString &note);
+
 Q_SIGNALS:
     void globalUrlPreviewEnabledChanged();
     void labelChanged();