fix: wrap streaming reader in try/finally to release lock and prevent resource leaks

Partially addresses #112. The streaming reader in openaiStreamToAnthropic
had no error handling - if an error occurred during streaming, the reader
lock was never released. Wrapped the while loop in try/finally to ensure
reader.releaseLock() is always called.

src/services/api/openaiShim.ts

@@ -412,15 +412,16 @@ async function* openaiStreamToAnthropic(
   const decoder = new TextDecoder()
   let buffer = ''
 
-  while (true) {
-    const { done, value } = await reader.read()
-    if (done) break
+  try {
+    while (true) {
+      const { done, value } = await reader.read()
+      if (done) break
 
-    buffer += decoder.decode(value, { stream: true })
-    const lines = buffer.split('\n')
-    buffer = lines.pop() ?? ''
+      buffer += decoder.decode(value, { stream: true })
+      const lines = buffer.split('\n')
+      buffer = lines.pop() ?? ''
 
-    for (const line of lines) {
+      for (const line of lines) {
       const trimmed = line.trim()
       if (!trimmed || trimmed === 'data: [DONE]') continue
       if (!trimmed.startsWith('data: ')) continue
@@ -566,6 +567,9 @@ async function* openaiStreamToAnthropic(
         hasEmittedFinalUsage = true
       }
     }
+    }
+  } finally {
+    reader.releaseLock()
   }
 
   yield { type: 'message_stop' }