perf: 优化内存与遥测管理，启用 Vite minify

- 禁用 HISTORY_SNIP feature flag 并新增 proactiveTruncate 防止无 compact_boundary 时内存无限增长
- 跳过未启用 telemetry 时的 OTel 初始化，防止长会话 PerformanceMeasure 堆积
- OTel 导出遇 401/403 自动关闭 reader，防止 handle 泄漏
- Vite 构建启用 minify

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/services/compact/snipCompact.ts

@@ -163,3 +163,77 @@ export function isSnipRuntimeEnabled(): boolean {
 export function shouldNudgeForSnips(messages: Message[]): boolean {
   return messages.length >= SNIP_NUDGE_THRESHOLD
 }
+
+/**
+ * Maximum total character length of message content before proactive
+ * truncation kicks in. ~150 MB of string data corresponds to roughly
+ * 1.5x the default 200k-token context window at 4 chars/token — well
+ * beyond what any model can actually use in a single request.
+ */
+const PROACTIVE_TRUNCATE_CHARS = 150_000_000
+
+/**
+ * Minimum number of messages to keep when falling back to tail-only
+ * retention (i.e. when no compact_boundary exists in the array).
+ */
+const PROACTIVE_TRUNCATE_MIN_TAIL = 50
+
+/**
+ * Proactively truncate old messages when the in-memory store grows too
+ * large. Unlike `snipCompactIfNeeded` (which waits for a snip_boundary
+ * from the API), this runs client-side after every push — ensuring
+ * unbounded growth cannot happen even when the API never returns a
+ * compact_boundary (e.g. third-party compat layers).
+ *
+ * Strategy:
+ * 1. If a `compact_boundary` exists, keep it and everything after it.
+ * 2. Otherwise, keep only the last `PROACTIVE_TRUNCATE_MIN_TAIL` messages.
+ *
+ * Returns the same array reference when no truncation is needed.
+ */
+export function proactiveTruncate(messages: Message[]): Message[] {
+  if (messages.length < PROACTIVE_TRUNCATE_MIN_TAIL) return messages
+
+  let totalChars = 0
+  for (const msg of messages) {
+    const content = msg.message?.content
+    if (typeof content === 'string') {
+      totalChars += content.length
+    } else if (Array.isArray(content)) {
+      for (const block of content) {
+        if (typeof block === 'string') {
+          totalChars += (block as string).length
+        } else if (block && typeof block === 'object') {
+          const obj = block as unknown as Record<string, unknown>
+          const text = obj.text ?? obj.content
+          if (typeof text === 'string') {
+            totalChars += text.length
+          }
+        }
+      }
+    }
+  }
+
+  if (totalChars < PROACTIVE_TRUNCATE_CHARS) return messages
+
+  // Find last compact_boundary — the standard anchor point
+  let boundaryIdx = -1
+  for (let i = messages.length - 1; i >= 0; i--) {
+    const msg = messages[i]!
+    if (
+      msg.type === 'system' &&
+      (msg as Record<string, unknown>).subtype === 'compact_boundary'
+    ) {
+      boundaryIdx = i
+      break
+    }
+  }
+
+  const keepFrom =
+    boundaryIdx >= 0
+      ? boundaryIdx
+      : Math.max(0, messages.length - PROACTIVE_TRUNCATE_MIN_TAIL)
+  if (keepFrom === 0) return messages
+
+  return messages.slice(keepFrom)
+}