Refactor Skill Tree Picker and Catalog Functions for Clarity and Efficiency

- Simplified the rendering of skill group labels in `SkillTreePickerPanel` for improved readability.
- Updated comments in `skillCatalogTree.js` to clarify the structure of expandable nodes and default expansion behavior.
- Refactored the skill catalog tree building logic to streamline the mapping of categories and skills, enhancing performance and maintainability.
- Adjusted tests in `skillCatalogTree.test.js` to reflect changes in the structure of skill nodes, ensuring accurate validation of functionality.

frontend/src/app.css

@@ -5320,12 +5320,6 @@ html.modal-scroll-locked .app-main {
   line-height: 1.35;
 }
 
-.skill-tree__group-label--skill-group {
-  font-weight: 500;
-  color: var(--text2);
-  font-size: 0.84rem;
-}
-
 .multi-assoc-block {
   border: 1px solid var(--border);
   border-radius: 8px;

frontend/src/components/SkillTreePickerPanel.jsx

@@ -55,11 +55,7 @@ function SkillTreeNodes({ nodes, depth, expanded, exclude, onToggle, onPickSkill
           ) : (
             <span className="skill-tree__toggle-spacer" aria-hidden />
           )}
-          <span
-            className={`skill-tree__group-label skill-tree__group-label--${node.type}${
-              node.type === 'skillGroup' ? ' skill-tree__group-label--skill-group' : ''
-            }`}
-          >
+          <span className={`skill-tree__group-label skill-tree__group-label--${node.type}`}>
             {node.label}
           </span>
         </div>
@@ -82,7 +78,7 @@ function SkillTreeNodes({ nodes, depth, expanded, exclude, onToggle, onPickSkill
 }
 
 /**
- * Ausklappbare Baumliste: Hauptgruppe → Kategorie (beide standard offen) → Fähigkeiten-Gruppe (standard zu).
+ * Ausklappbare Baumliste: Hauptgruppe → Kategorie → Fähigkeit (Hauptgruppe und Kategorie standard offen).
  */
 export default function SkillTreePickerPanel({
   skills = [],

frontend/src/utils/skillCatalogTree.js

@@ -80,33 +80,18 @@ export function buildSkillCatalogTree(skills) {
           if (a.sortOrder !== b.sortOrder) return a.sortOrder - b.sortOrder
           return a.label.localeCompare(b.label, 'de')
         })
-        .map((cat) => {
-          const skillLeaves = [...cat.skills].sort(bySortThenName).map((skill) => ({
+        .map((cat) => ({
+          key: cat.key,
+          type: cat.type,
+          label: cat.label,
+          children: [...cat.skills].sort(bySortThenName).map((skill) => ({
             key: `s-${skill.id}`,
             type: 'skill',
             label: (skill.name || '').trim() || `#${skill.id}`,
             skillId: Number(skill.id),
             skill,
-          }))
-          const n = skillLeaves.length
-          return {
-            key: cat.key,
-            type: cat.type,
-            label: cat.label,
-            children:
-              n > 0
-                ? [
-                    {
-                      key: `${cat.key}-skills`,
-                      type: 'skillGroup',
-                      label: n === 1 ? '1 Fähigkeit' : `${n} Fähigkeiten`,
-                      skillCount: n,
-                      children: skillLeaves,
-                    },
-                  ]
-                : [],
-          }
-        }),
+          })),
+        })),
     }))
 }
 
@@ -132,8 +117,7 @@ export function collectSkillLeavesFromTree(tree, excludeIds) {
           out.push({ id: n.skillId, label: n.label, pathLabel, skill: n.skill })
         }
       } else if (n.children?.length) {
-        const nextPath = n.type === 'skillGroup' ? pathParts : [...pathParts, n.label]
-        walk(n.children, nextPath)
+        walk(n.children, [...pathParts, n.label])
       }
     }
   }
@@ -153,9 +137,6 @@ export function filterSkillTreeByQuery(tree, query) {
       if (n.type === 'skill') {
         const hay = `${n.label} ${skillCatalogPathLabel(n.skill)}`.toLowerCase()
         if (hay.includes(q)) result.push(n)
-      } else if (n.type === 'skillGroup') {
-        const kids = filterNodes(n.children || [])
-        if (kids.length) result.push({ ...n, children: kids })
       } else {
         const kids = filterNodes(n.children || [])
         if (kids.length) result.push({ ...n, children: kids })
@@ -166,7 +147,7 @@ export function filterSkillTreeByQuery(tree, query) {
   return filterNodes(tree)
 }
 
-/** Alle aufklappbaren Knoten (inkl. Fähigkeiten-Gruppen unter Kategorien). */
+/** Alle aufklappbaren Knoten (Hauptgruppe und Kategorie). */
 export function allExpandableKeys(tree) {
   const keys = []
   const walk = (nodes) => {
@@ -181,7 +162,7 @@ export function allExpandableKeys(tree) {
   return keys
 }
 
-/** Standard: Hauptgruppe + Kategorie offen, Fähigkeiten-Liste zugeklappt. */
+/** Standard: Hauptgruppe und Kategorie aufgeklappt (Fähigkeiten direkt darunter sichtbar). */
 export function defaultExpandedKeysForSkillTree(tree) {
   const keys = []
   const walk = (nodes) => {

frontend/src/utils/skillCatalogTree.test.js

@@ -44,9 +44,9 @@ describe('skillCatalogTree', () => {
     expect(tree[0].label).toBe('Karate')
     expect(tree[0].children).toHaveLength(2)
     expect(tree[0].children[0].label).toBe('Kata')
-    const kataSkills = tree[0].children[0].children[0]
-    expect(kataSkills.type).toBe('skillGroup')
-    expect(kataSkills.children[0].skillId).toBe(2)
+    const kataSkill = tree[0].children[0].children[0]
+    expect(kataSkill.type).toBe('skill')
+    expect(kataSkill.skillId).toBe(2)
   })
 
   it('defaultExpandedKeysForSkillTree opens main and category only', () => {
@@ -54,7 +54,7 @@ describe('skillCatalogTree', () => {
     const keys = defaultExpandedKeysForSkillTree(tree)
     expect(keys).toContain('m-10')
     expect(keys.some((k) => k.includes('c-21'))).toBe(true)
-    expect(keys.some((k) => k.endsWith('-skills'))).toBe(false)
+    expect(keys.some((k) => k.startsWith('s-'))).toBe(false)
   })
 
   it('skillCatalogPathLabel', () => {
@@ -72,8 +72,7 @@ describe('skillCatalogTree', () => {
     const tree = buildSkillCatalogTree(sample)
     const filtered = filterSkillTreeByQuery(tree, 'dachi')
     const kihon = filtered[0].children.find((c) => c.label === 'Kihon')
-    const group = kihon?.children?.[0]
-    expect(group?.children?.some((s) => s.skillId === 1)).toBe(true)
+    expect(kihon?.children?.some((s) => s.skillId === 1)).toBe(true)
   })
 
   it('catalogSkillsForSelection lists unassigned buckets', () => {