fix: upsert traces to handle duplicate IDs from intermediate flushes

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-Claude)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

packages/opencode-plugin/package.json

@@ -1,6 +1,6 @@
 {
   "name": "opencode-agentlens",
-  "version": "0.1.1",
+  "version": "0.1.2",
   "description": "OpenCode plugin for AgentLens — trace your coding agent's decisions, tool calls, and sessions",
   "type": "module",
   "main": "./dist/index.cjs",