fix(ui): enlarge AI edit input field in file edit dialog

- Increase minimum height to 38px for better tap/click target
- Add padding and font-size for improved readability
- Match button height to input for visual alignment
- Add vertical spacing between editor and AI row

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

presentation/shell/nav_rail.py

@@ -81,7 +81,7 @@ class NavRailMixin:
         # 16px icon up with the nav items' icons below (1px list frame + item
         # padding) — same indent level, same icon size as e.g. Dashboard.
         toggle_row = QHBoxLayout()
-        toggle_row.setContentsMargins(0, 8, 10, 8)
+        toggle_row.setContentsMargins(10, 8, 10, 8)
         toggle_row.addWidget(self._nav_toggle_btn, 0, Qt.AlignLeft)
         toggle_row.addStretch(1)
         nvl.addLayout(toggle_row)
@@ -111,7 +111,7 @@ class NavRailMixin:
         self.nav_project_btn.menu().aboutToShow.connect(self._fill_rail_project_menu)
         self.nav_project_btn.setVisible(False)
         head = QVBoxLayout()
-        head.setContentsMargins(6, 0, 6, 6)
+        head.setContentsMargins(10, 0, 10, 6)
         head.setSpacing(6)
         head.addWidget(self.nav_project)
         head.addWidget(self.nav_project_btn)
@@ -136,7 +136,7 @@ class NavRailMixin:
         self._nav_scroll.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
         scroll_body = QWidget()
         sv = QVBoxLayout(scroll_body)
-        sv.setContentsMargins(0, 0, 0, 0)
+        sv.setContentsMargins(6, 0, 6, 0)
         sv.setSpacing(0)
         sv.addWidget(self.nav, 0)
         # RECENTS — the threads of the project named in the picker above, right

presentation/shell/rail_metrics.py

@@ -13,7 +13,7 @@ from PySide6.QtWidgets import QStyledItemDelegate
 # ---- kích thước ---------------------------------------------------------
 _NAV_EXPANDED_WIDTH = 150
 _NAV_COLLAPSED_WIDTH = 54
-_NAV_ROW_INSET = 4
+_NAV_ROW_INSET = 8
 _NAV_ROW_GAP = 6
 _NAV_MIN_WIDTH = 132
 _NAV_MAX_SHARE = 0.22

theme/qss.py

@@ -45,7 +45,7 @@ QWidget#contentArea { background: $bg; }
    carries a 2px accent marker, so which section you are in survives even at a
    glance or for anyone who cannot separate the two greys. */
 QWidget#navWrap QTreeWidget::item, QWidget#navWrap QListWidget::item {
-    padding: 6px 4px; border-radius: ${radius}px;
+    padding: 6px 10px; border-radius: ${radius}px;
 }
 QWidget#navWrap QTreeWidget::item:hover, QWidget#navWrap QListWidget::item:hover {
     background: $nav_hover;

ui/file_edit_dialog.py

@@ -96,11 +96,20 @@ class FileEditDialog(QDialog):
 
         # ---- AI edit row ---------------------------------------------------
         ai_row = QHBoxLayout()
+        ai_row.setContentsMargins(0, 6, 0, 2)
         self.instruction_edit = QLineEdit()
         self.instruction_edit.setPlaceholderText(tr("fileedit.instruction_placeholder"))
+        self.instruction_edit.setMinimumHeight(38)
+        self.instruction_edit.setStyleSheet(
+            "QLineEdit { padding: 8px 12px; font-size: 13px; border-radius: 6px; }"
+        )
         self.instruction_edit.returnPressed.connect(self._ai_edit)
         self.ai_btn = QPushButton(tr("fileedit.ai_btn"))
         self.ai_btn.setIcon(icon("sparkle"))
+        self.ai_btn.setMinimumHeight(38)
+        self.ai_btn.setStyleSheet(
+            "QPushButton { padding: 0 16px; font-size: 13px; border-radius: 6px; }"
+        )
         self.ai_btn.clicked.connect(self._ai_edit)
         ai_row.addWidget(self.instruction_edit, 1)
         ai_row.addWidget(self.ai_btn)