test(good-fences): lent a mower, a Think agent mows (red)

The first end-to-end test: a Project Think agent, on the real model,
writes code that runs in a dynamic worker and drives a mower; the test
counts the cells cut, and saves the turn to itest-output/.

Installs @cloudflare/think, @cloudflare/codemode, agents, ai,
workers-ai-provider, zod. The model-test worker now has a main entry,
the Neighbor DO, and a LOADER binding.

Red: src/worker.ts doesn't exist yet.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

good-fences/wrangler.model-tests.jsonc

@@ -2,6 +2,15 @@
 	"$schema": "node_modules/wrangler/config-schema.json",
 	// model integration tests: AI always runs remotely, and costs money
 	"name": "good-fences-model-tests",
+	"main": "./src/worker.ts",
 	"compatibility_date": "2026-10-01",
-	"ai": { "binding": "AI", "remote": true }
+	"compatibility_flags": ["nodejs_compat"],
+	"ai": { "binding": "AI", "remote": true },
+	"worker_loaders": [{ "binding": "LOADER" }],
+	"durable_objects": {
+		"bindings": [{ "name": "Neighbor", "class_name": "Neighbor" }]
+	},
+	"exports": {
+		"Neighbor": { "type": "durable-object", "storage": "sqlite" }
+	}
 }