feat(knowledge-base): Knowledge Base UI — browse/edit, modal, project links

- Knowledge Bases list page + sidebar entry + "+ New" create modal
- Detail page with a recursive structure tree: add/edit/delete topics,
  categories and facts inline, including name + description editing
- Create/metadata-edit modal (title, description)
- Project edit modal gains a link/remove knowledge base section
- Types and routes for /knowledge-bases and /knowledge-bases/:id
- Scoped .kb-* styles (contained panel, topic cards, hierarchy guides)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/App.tsx

@@ -8,6 +8,8 @@ import TasksPage from '@/pages/TasksPage'
 import TaskDetailPage from '@/pages/TaskDetailPage'
 import ProjectsPage from '@/pages/ProjectsPage'
 import ProjectDetailPage from '@/pages/ProjectDetailPage'
+import KnowledgeBasesPage from '@/pages/KnowledgeBasesPage'
+import KnowledgeBaseDetailPage from '@/pages/KnowledgeBaseDetailPage'
 import MilestonesPage from '@/pages/MilestonesPage'
 import MilestoneDetailPage from '@/pages/MilestoneDetailPage'
 import NotificationsPage from '@/pages/NotificationsPage'
@@ -130,6 +132,8 @@ export default function App() {
             <Route path="/tasks/:taskCode" element={<TaskDetailPage />} />
             <Route path="/projects" element={<ProjectsPage />} />
             <Route path="/projects/:id" element={<ProjectDetailPage />} />
+            <Route path="/knowledge-bases" element={<KnowledgeBasesPage />} />
+            <Route path="/knowledge-bases/:id" element={<KnowledgeBaseDetailPage />} />
             <Route path="/milestones" element={<MilestonesPage />} />
             <Route path="/milestones/:milestoneCode" element={<MilestoneDetailPage />} />
             <Route path="/proposals" element={<ProposalsPage />} />