fix(session-folders): persist via server endpoint, not client-built home path

Client previously built `${homeDirectory}/.config/openchamber/sessions-directories.json`
using client-side homeDirectory, which in some boot paths resolved to the
active workspace and wrote the file inside the project. Replace with
GET/POST /api/session-folders — server uses os.homedir() directly, so the
file always lands in ~/.config/openchamber/ regardless of client state.

packages/web/server/lib/opencode/core-routes.js

@@ -261,6 +261,7 @@ export const registerCommonRequestMiddleware = (app, dependencies) => {
       req.path.startsWith('/api/opencode') ||
       req.path.startsWith('/api/push') ||
       req.path.startsWith('/api/notifications') ||
+      req.path.startsWith('/api/session-folders') ||
       req.path.startsWith('/api/text') ||
       req.path.startsWith('/api/voice') ||
       req.path.startsWith('/api/tts') ||

packages/web/server/lib/opencode/feature-routes-runtime.js

@@ -3,6 +3,7 @@ import { registerQuotaRoutes } from '../quota/routes.js';
 import { registerGitHubRoutes } from '../github/routes.js';
 import { registerGitRoutes } from '../git/routes.js';
 import { registerMagicPromptRoutes } from '../magic-prompts/routes.js';
+import { registerSessionFoldersRoutes } from '../session-folders/routes.js';
 import { registerConfigEntityRoutes } from './config-entity-routes.js';
 import { registerSettingsUtilityRoutes } from './core-routes.js';
 import { registerProjectIconRoutes } from './project-icon-routes.js';
@@ -216,6 +217,11 @@ export const createFeatureRoutesRuntime = (dependencies) => {
       path,
       openchamberDataDir,
     });
+    registerSessionFoldersRoutes(app, {
+      fsPromises,
+      path,
+      openchamberDataDir,
+    });
     registerFsRoutes(app, {
       os,
       path,