Co4E step config as collapsible sections; tighter Kanban lanes; Output panel fills its column

- co4e_config_panel: StepConfigPanel reorganized into four collapsible,
  borderless sections (Co ban / Model & Quyen / Skills & Tep / Agent song
  song) instead of one long form. Agent song song is its own section,
  shown only for parallel-variant steps. Fixes a QVBoxLayout without a
  trailing stretch that was handing every section an equal share of the
  scroll area's leftover height instead of sizing to content.
- schedule_task_tab / theme: Kanban board lane gutters and per-lane
  margins trimmed so the seven lanes read their card content more
  clearly on a laptop-width window.
- chat_panel / widgets: the Output Files list in Cowork/Code no longer
  stops at a fixed height with empty panel below it - it now fills the
  column down to the composer.
- composer: Attach/Send/Stop buttons match the input box's height and
  align to its top/bottom edge instead of floating centered beside it.
- app.py: the sidebar's "All projects" link reads as a link (italic,
  accent color) instead of a plain row.
- i18n: labels for the three renamed Co4E section headers (VI/EN/JA).

app.py

@@ -7,7 +7,7 @@ from pathlib import Path
 from typing import List
 
 from PySide6.QtCore import Qt, QTimer
-from PySide6.QtGui import QGuiApplication, QIcon
+from PySide6.QtGui import QColor, QGuiApplication, QIcon
 from PySide6.QtWidgets import (
     QStyledItemDelegate,
     QApplication, QComboBox, QHBoxLayout, QLabel, QMainWindow, QMenu,
@@ -747,9 +747,14 @@ class MainWindow(QMainWindow):
             it = QTreeWidgetItem([tr("sidebar.empty")])
             it.setDisabled(True)
             tree.addTopLevelItem(it)
-        # The way back to everything the rail cannot show.
+        # The way back to everything the rail cannot show — styled as a link
+        # (italic, accent-colored) so it reads as "go elsewhere", not another row.
         more = QTreeWidgetItem([tr("app.nav.all_projects")])
         more.setData(0, Qt.UserRole, {"all": True})
+        more_font = more.font(0)
+        more_font.setItalic(True)
+        more.setFont(0, more_font)
+        more.setForeground(0, QColor(current_palette().accent))
         tree.addTopLevelItem(more)
         tree.blockSignals(blocked)
         self.nav_recents_hdr.setVisible(not self._nav_collapsed)