style(ui): login dialog matches Steam-layout in Prism dark

Same skeleton as the conflict dialog: header (Prism-green badge +
uppercase title), body copy, content, foot row.

Specifics:
  - badge: '+' on Prism-green circle (vs the conflict's '!' on
    light gray) — green reads as 'setup / new', not warning
  - command callout: monospace, green text, dark inset card
  - token input: monospace, dark inset, green focus border, green
    selection highlight
  - 'Skip cloud sync' = secondary (dark surface, green hover border)
  - 'Save and continue' = primary (Prism-green fill, black text)

Same Enter-to-submit + format validation behavior as before;
on-screen error reuses Prism's BrightText red.

cloud_sync/ui_qt.py

@@ -191,12 +191,94 @@ class QtProgressWindow:
 # ---------------------------------------------------------------------------
 
 
+_LOGIN_QSS = """
+QDialog { background: #313131; }
+QLabel#title {
+    color: white;
+    font-size: 20pt;
+    font-weight: bold;
+    letter-spacing: 2px;
+}
+QLabel#badge {
+    color: #313131;
+    background: #96db59;
+    border-radius: 16px;
+    font-size: 20pt;
+    font-weight: bold;
+    qproperty-alignment: AlignCenter;
+    min-width: 32px;
+    max-width: 32px;
+    min-height: 32px;
+    max-height: 32px;
+}
+QLabel#body {
+    color: #c8c8c8;
+    font-size: 10pt;
+}
+QLabel#hint {
+    color: #8a8a8a;
+    font-size: 9pt;
+}
+QLabel#error {
+    color: #ff7373;
+    font-size: 9pt;
+}
+QLabel#cmd {
+    color: #96db59;
+    background: #222222;
+    border: 1px solid #3a3a3a;
+    border-radius: 3px;
+    padding: 6px 10px;
+    font-family: "JetBrains Mono", "Source Code Pro", Menlo, Consolas, monospace;
+    font-size: 10pt;
+}
+QLineEdit#token {
+    background: #222222;
+    border: 1px solid #3a3a3a;
+    border-radius: 3px;
+    padding: 8px 10px;
+    color: white;
+    font-family: "JetBrains Mono", "Source Code Pro", Menlo, Consolas, monospace;
+    font-size: 10pt;
+    selection-background-color: #96db59;
+    selection-color: black;
+}
+QLineEdit#token:focus { border: 1px solid #96db59; }
+QPushButton#secondary {
+    background: #303030;
+    color: white;
+    border: 1px solid #4a4a4a;
+    border-radius: 2px;
+    padding: 8px 20px;
+    font-size: 10pt;
+}
+QPushButton#secondary:hover { background: #3a3a3a; border-color: #96db59; }
+QPushButton#secondary:pressed { background: #222222; }
+QPushButton#primary {
+    background: #96db59;
+    color: #1a1a1a;
+    border: none;
+    border-radius: 2px;
+    padding: 8px 24px;
+    font-size: 10pt;
+    font-weight: bold;
+}
+QPushButton#primary:hover { background: #a8e670; }
+QPushButton#primary:pressed { background: #7fbf48; }
+QPushButton#primary:disabled { background: #4a5a3a; color: #888888; }
+"""
+
+
 def prompt_login_qt() -> str | None:
     """Modal dialog to collect a fresh ``discord_id:password`` token.
 
     Returned string is the validated raw token (caller writes to disk).
     Returns ``None`` if the user picked "Skip cloud sync" or closed the
     dialog — caller should treat that as "don't sync, don't block launch."
+
+    Visually matches the conflict dialog: Prism dark surface, circled
+    badge + uppercase title, monospace input field with Prism-green
+    focus accent, primary "Save and continue" button in Prism green.
     """
     QtWidgets, QtCore, _ = import_qt()
     app_existed = QtWidgets.QApplication.instance() is not None
@@ -205,58 +287,79 @@ def prompt_login_qt() -> str | None:
         _apply_prism_dark(app)
 
     dialog = QtWidgets.QDialog()
-    dialog.setWindowTitle("Cloud sync — first time setup")
-    dialog.setFixedSize(480, 260)
+    dialog.setWindowTitle("Cloud sync — connect account")
+    dialog.setFixedSize(560, 360)
+    dialog.setStyleSheet(_LOGIN_QSS)
 
-    layout = QtWidgets.QVBoxLayout(dialog)
-    layout.setContentsMargins(20, 20, 20, 20)
-    layout.setSpacing(10)
+    outer = QtWidgets.QVBoxLayout(dialog)
+    outer.setContentsMargins(28, 24, 28, 20)
+    outer.setSpacing(14)
 
-    title = QtWidgets.QLabel("Connect to cloud save")
-    font = title.font()
-    font.setBold(True)
-    font.setPointSize(font.pointSize() + 2)
-    title.setFont(font)
-    layout.addWidget(title)
+    header = QtWidgets.QHBoxLayout()
+    header.setSpacing(12)
+    badge = QtWidgets.QLabel("+")
+    badge.setObjectName("badge")
+    header.addWidget(badge)
+    title = QtWidgets.QLabel("CONNECT CLOUD SAVE")
+    title.setObjectName("title")
+    header.addWidget(title)
+    header.addStretch(1)
+    outer.addLayout(header)
 
     body = QtWidgets.QLabel(
-        "In Discord, message the bot:\n"
-        "    /cloud register\n\n"
-        "It will DM you a one-line token. Paste it below:"
+        "To enable cross-machine save sync, message the Discord bot to "
+        "register this account. The bot will DM you a one-line token — "
+        "paste it below."
     )
+    body.setObjectName("body")
     body.setWordWrap(True)
-    layout.addWidget(body)
+    outer.addWidget(body)
+
+    cmd = QtWidgets.QLabel("/cloud register")
+    cmd.setObjectName("cmd")
+    cmd.setTextInteractionFlags(QtCore.Qt.TextInteractionFlag.TextSelectableByMouse)
+    cmd.setFixedWidth(180)
+    outer.addWidget(cmd)
+
+    outer.addSpacing(4)
+
+    field_label = QtWidgets.QLabel("Token")
+    field_label.setObjectName("hint")
+    outer.addWidget(field_label)
 
     field = QtWidgets.QLineEdit()
-    field.setPlaceholderText("123456789012345678:a1b2c3d4…")
+    field.setObjectName("token")
+    field.setPlaceholderText("123456789012345678:a1b2c3d4e5f6…")
     field.setEchoMode(QtWidgets.QLineEdit.EchoMode.Password)
-    layout.addWidget(field)
+    outer.addWidget(field)
 
     error = QtWidgets.QLabel("")
-    error.setStyleSheet("color: #ff6b6b;")
-    layout.addWidget(error)
+    error.setObjectName("error")
+    outer.addWidget(error)
 
-    layout.addStretch(1)
+    outer.addStretch(1)
 
-    button_row = QtWidgets.QHBoxLayout()
+    foot = QtWidgets.QHBoxLayout()
     skip = QtWidgets.QPushButton("Skip cloud sync")
-    button_row.addWidget(skip)
-    button_row.addStretch(1)
+    skip.setObjectName("secondary")
+    foot.addWidget(skip)
+    foot.addStretch(1)
     save = QtWidgets.QPushButton("Save and continue")
+    save.setObjectName("primary")
     save.setDefault(True)
-    button_row.addWidget(save)
-    layout.addLayout(button_row)
+    foot.addWidget(save)
+    outer.addLayout(foot)
 
     chosen: dict[str, str | None] = {"value": None}
 
     def on_save() -> None:
         token = field.text().strip()
         if ":" not in token:
-            error.setText("Token must be discord_id:password")
+            error.setText("Token must look like discord_id:password.")
             return
-        head, sep, tail = token.partition(":")
+        head, _sep, tail = token.partition(":")
         if not head.isdigit() or not tail:
-            error.setText("discord_id must be numeric; password must be non-empty")
+            error.setText("discord_id must be numeric and password non-empty.")
             return
         chosen["value"] = token
         dialog.accept()