fix(app): replace CORS Access-Control-Allow-Origin * with explicit localhost origin

Add setCorsHeaders() and handleCorsOptions() helpers in server/dev-auth.ts.
Replace wildcard CORS origin with http://localhost:5173 in all Vite plugins
and claude-proxy.ts. Include Authorization in allowed CORS headers.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/app/server/claude-proxy.ts

@@ -3,7 +3,7 @@ import { createServer } from 'http'
 import { readFileSync, existsSync } from 'fs'
 import { resolve, dirname } from 'path'
 import { fileURLToPath } from 'url'
-import { validateDevAuth } from './dev-auth.js'
+import { validateDevAuth, handleCorsOptions } from './dev-auth.js'
 
 const __dirname = dirname(fileURLToPath(import.meta.url))
 
@@ -209,7 +209,7 @@ async function streamOpenRouterProxy(
   res: import('http').ServerResponse,
 ): Promise<void> {
   if (!OPENROUTER_API_KEY) {
-    res.writeHead(500, { 'Content-Type': 'application/json', 'Access-Control-Allow-Origin': '*' })
+    res.writeHead(500, { 'Content-Type': 'application/json', 'Access-Control-Allow-Origin': 'http://localhost:5173' })
     res.end(JSON.stringify({ error: 'OPENROUTER_API_KEY not configured on server' }))
     return
   }
@@ -218,7 +218,7 @@ async function streamOpenRouterProxy(
     'Content-Type': 'text/event-stream',
     'Cache-Control': 'no-cache',
     'Connection': 'keep-alive',
-    'Access-Control-Allow-Origin': '*',
+    'Access-Control-Allow-Origin': 'http://localhost:5173',
     'X-Accel-Buffering': 'no',
   })
 
@@ -280,12 +280,7 @@ async function streamOpenRouterProxy(
 
 const server = createServer((req, res) => {
   if (req.method === 'OPTIONS') {
-    res.writeHead(204, {
-      'Access-Control-Allow-Origin': '*',
-      'Access-Control-Allow-Methods': 'POST, OPTIONS',
-      'Access-Control-Allow-Headers': 'Content-Type',
-    })
-    res.end()
+    handleCorsOptions(res)
     return
   }
 
@@ -316,7 +311,7 @@ const server = createServer((req, res) => {
           'Content-Type': 'text/event-stream',
           'Cache-Control': 'no-cache',
           'Connection': 'keep-alive',
-          'Access-Control-Allow-Origin': '*',
+          'Access-Control-Allow-Origin': 'http://localhost:5173',
           'X-Accel-Buffering': 'no',
         })
         streamViaAnthropicApi(model, system, messages ?? [], res)
@@ -378,7 +373,7 @@ const server = createServer((req, res) => {
         'Content-Type': 'text/event-stream',
         'Cache-Control': 'no-cache',
         'Connection': 'keep-alive',
-        'Access-Control-Allow-Origin': '*',
+        'Access-Control-Allow-Origin': 'http://localhost:5173',
         'X-Accel-Buffering': 'no',
       })
 
@@ -437,7 +432,7 @@ const server = createServer((req, res) => {
       console.error('[proxy] Parse error:', err)
       res.writeHead(400, {
         'Content-Type': 'application/json',
-        'Access-Control-Allow-Origin': '*',
+        'Access-Control-Allow-Origin': 'http://localhost:5173',
       })
       res.end(JSON.stringify({ error: String(err) }))
     }