Update @opencode-ai/plugin and SDK to v1.2.x and align system transform handler signature

- Bump @opencode-ai/plugin ^1.1.19 → ^1.2.16, @opencode-ai/sdk ^1.1.19 → ^1.2.17
- Update system-transform handler input type to match new plugin contract (optional sessionID, required model)
- Add @opencode-ai/sdk override in bun.lock

🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

package.json

@@ -56,8 +56,8 @@
     "@clack/prompts": "^0.11.0",
     "@code-yeongyu/comment-checker": "^0.7.0",
     "@modelcontextprotocol/sdk": "^1.25.2",
-    "@opencode-ai/plugin": "^1.1.19",
-    "@opencode-ai/sdk": "^1.1.19",
+    "@opencode-ai/plugin": "^1.2.16",
+    "@opencode-ai/sdk": "^1.2.17",
     "commander": "^14.0.2",
     "detect-libc": "^2.0.0",
     "diff": "^8.0.3",
@@ -87,6 +87,9 @@
     "oh-my-opencode-windows-x64": "3.10.0",
     "oh-my-opencode-windows-x64-baseline": "3.10.0"
   },
+  "overrides": {
+    "@opencode-ai/sdk": "^1.2.17"
+  },
   "trustedDependencies": [
     "@ast-grep/cli",
     "@ast-grep/napi",