fix(nav): register Journal/Planner shapes, fix headerColor crash, enable academic week expansion

Bugs fixed:
- 'cc-teacher-timetable-node' missing from NODE_TYPE_THEMES caused
  Cannot read properties of undefined (reading 'headerColor') crash
  when clicking My Timetable
- 'cc-journal-node' and 'cc-planner-node' had no shape utils registered,
  causing 'No shape util found for type' error on Journal/Planner click
- Added null safety (?? fallback) to getNodeTheme to prevent future crashes
  from any other unmapped type
- Removed AcademicWeek from canExpand exclusion so weeks can be expanded
  to show individual academic days

Added:
- CCJournalNodeShapeUtil and CCPlannerNodeShapeUtil (stub shapes)
- CCJournalNodeProps and CCPlannerNodeProps types
- Journal/Planner added to CCNodeTypes, ccGraphShapeProps, NODE_TYPE_THEMES
- 'cc-department-structure-node' mapping added to NODE_TYPE_THEMES

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

src/utils/tldraw/cc-base/cc-graph/CCPlannerNodeShapeUtil.tsx

@@ -0,0 +1,36 @@
+import { CCBaseShapeUtil } from '../CCBaseShapeUtil'
+import { CCBaseShape } from '../cc-types'
+import { ccGraphShapeProps, getDefaultCCPlannerNodeProps } from './cc-graph-props'
+import { getNodeStyles, NODE_THEMES, NODE_TYPE_THEMES } from './cc-graph-styles'
+import { CCPlannerNodeProps } from './cc-graph-types'
+
+export interface CCPlannerNodeShape extends CCBaseShape {
+  type: 'cc-planner-node'
+  props: CCPlannerNodeProps
+}
+
+export class CCPlannerNodeShapeUtil extends CCBaseShapeUtil<CCPlannerNodeShape> {
+  static type = 'cc-planner-node' as const
+  static props = ccGraphShapeProps['cc-planner-node']
+
+  getDefaultProps(): CCPlannerNodeShape['props'] {
+    const defaultProps = getDefaultCCPlannerNodeProps()
+    const theme = NODE_THEMES[NODE_TYPE_THEMES[CCPlannerNodeShapeUtil.type]] ?? NODE_THEMES.resource
+    return {
+      ...defaultProps,
+      headerColor: theme.headerColor,
+    }
+  }
+
+  DefaultComponent = () => null
+
+  renderContent = (shape: CCPlannerNodeShape) => {
+    const styles = getNodeStyles(shape.type)
+    return (
+      <div style={styles.container}>
+        <div style={{ ...styles.header, color: shape.props.headerColor }}>Planner</div>
+        <div style={{ fontSize: 11, color: 'var(--color-text-2)' }}>Lesson and weekly planner</div>
+      </div>
+    )
+  }
+}