feat(settings): host Claude config as a tab in Settings

Settings becomes a tabbed shell (SettingsHub) with one tab per AI tool:
Dashboard (existing settings), Claude Code (CcConfig), plus Codex and
Cursor placeholders. Active tab lives in the ?tool= query param, and the
old /cc-config route redirects to /settings?tool=claude-code. The
standalone sidebar entry is dropped.

Adding a tool is one entry in TOOL_TABS plus its i18n label.

client/README.md

@@ -448,9 +448,9 @@ graph TB
     Detail["/sessions/:id"]
     Feed["/activity"]
     Workflows["/workflows"]
-    CcConfig["/cc-config"]
+    CcConfig["/cc-config (redirect)"]
     Run["/run"]
-    Settings["/settings"]
+    Settings["/settings (tabs: dashboard | claude-code | ...)"]
     NF["/* (NotFound)"]
 
     Root --> Dashboard & Sessions & Detail & Feed & Workflows & CcConfig & Run & Settings & NF
@@ -476,9 +476,10 @@ function App() {
           <Route path="sessions/:id" element={<SessionDetail />} />
           <Route path="activity" element={<ActivityFeed />} />
           <Route path="workflows" element={<Workflows />} />
-          <Route path="cc-config" element={<CcConfig />} />
+          {/* legacy path - Claude config now lives in a Settings tab */}
+          <Route path="cc-config" element={<Navigate to="/settings?tool=claude-code" replace />} />
           <Route path="run" element={<Run />} />
-          <Route path="settings" element={<Settings />} />
+          <Route path="settings" element={<SettingsHub />} />
           <Route path="*" element={<NotFound />} />
         </Route>
       </Routes>