feat(agent): migrate OpenCode 2 runtime and sandbox tools

Upgrade the runtime and native plugin API to OpenCode 2.0.24. Restore
session-scoped learning, credential renewal, typed project queries and
controlled frontend actions from the legacy Agent.

Replace host Shell execution with an approved Landlock/seccomp executor
and persistent per-session workspaces. Add typed Bocha search and Tianditu
geocoding bridges using the owning session credential. Require a working
kernel sandbox before startup and persist workspace files in deployments.

Validation completed before this commit: TypeScript checks, 150 Bun tests,
Docker build and UID 10001 sandbox execution, native Shell approval and
session recovery. Tianditu succeeded; Bocha currently reports exhausted
account quota. Unrelated investigation-report contract work is excluded.

.opencode/tools/locate_features.ts

@@ -0,0 +1,7 @@
+import { tool } from "../tool.js";
+import { executeFrontendAction } from "./frontend_action.js";
+export default tool({
+  description: "在当前供水地图定位资产并等待浏览器执行回执。返回已定位和未找到的 ID，失败时不得宣称成功。",
+  args: { layer: tool.schema.enum(["junctions", "pipes", "valves", "pumps", "tanks", "reservoirs", "scada"]), feature_ids: tool.schema.array(tool.schema.string().min(1).max(128)).min(1).max(100), reason: tool.schema.string().max(2000) },
+  async execute(args, context) { return executeFrontendAction("locate_features", args, context); },
+});