feat: add Behavior settings page for global AGENTS.md (#1079)

* feat: add Behavior settings page for global AGENTS.md

- Add new 'Behavior' settings page to manage global system prompt
- Sync global behavior prompt to ~/.config/opencode/AGENTS.md
- Add GET/PUT /api/behavior/agents-md endpoints with 1MB size limit
- Add AbortController guards and parallel fetches in BehaviorPage
- Add i18n translations for en, es, ko, pt-BR, uk, zh-CN
- Add globalBehaviorPrompt to DesktopSettings type and sanitizer
- Add /api/behavior to express.json() body-parser whitelist
- Ensure atomic save: AGENTS.md written before settings updated

* fix: address Greptile review feedback

- Rename misleading 'trimmed' variable to 'value' in settings-helpers.js
- Add Content-Length guard for /api/behavior before 50mb JSON parser
- Use express.json({ limit: '1mb' }) for behavior endpoints
- Add actual translations for es, ko, pt-BR, uk, zh-CN locales

* fix(vscode): support behavior settings endpoint

* fix(behavior): wait for settings persistence

* fix(behavior): end agents file with newline

* fix(behavior): avoid duplicate textarea resize handles

* fix(behavior): clarify global rules copy

* fix(behavior): move rules note into tooltip

---------

Co-authored-by: Bohdan Triapitsyn <artmore@protonmail.com>

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

@@ -454,7 +454,13 @@ export const registerCommonRequestMiddleware = (app, dependencies) => {
   const { express } = dependencies;
 
   app.use((req, res, next) => {
-    if (
+    if (req.path.startsWith('/api/behavior')) {
+      const contentLength = parseInt(req.headers['content-length'] || '0', 10);
+      if (contentLength > 1024 * 1024) {
+        return res.status(413).json({ error: 'Content exceeds maximum size of 1048576 bytes' });
+      }
+      express.json({ limit: '1mb' })(req, res, next);
+    } else if (
       req.path.startsWith('/api/config/agents') ||
       req.path.startsWith('/api/config/commands') ||
       req.path.startsWith('/api/config/mcp') ||