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.

tests/chat/models.test.ts

@@ -19,7 +19,7 @@ describe("agent model config", () => {
   });
 
   it("validates supported model ids", () => {
-    expect(isSupportedModel("deepseek/deepseek-v4-flash")).toBe(true);
+    expect(isSupportedModel(supportedModels[0]!)).toBe(true);
     expect(isSupportedModel("unknown/model")).toBe(false);
   });