feat(turbo): turbo gen feature generator (Phase 1, single-entity)

Adds `pnpm turbo gen feature` to scaffold a Lazar-conformant feature
package matching the navigation reference shape: entity + Zod schema,
single use case (`get<Entity>`), controller, mock + Payload-stub real
repository (with span + capture), DI module/container/symbols, and tRPC
router with full BAD_REQUEST/NOT_FOUND error mapping. The generated
`bind-production.ts` and `bind-dev-seed.ts` compose the post-R44
`withSpan(tracer, opts, withCapture(logger, tags, factory(deps)))`
sandwich at bind time.

Verified by generating a sample `packages/example/` feature and running
`pnpm --filter @repo/example lint typecheck test` — all three pass
(9 test files, 25 tests). Cleaned up after verification so no example
package is committed.

Phase-1 limitations (documented in `docs/guides/scaffolding-a-feature.md`
and printed by the generator on success): no Payload CMS templates, no
React Query helpers, faker-driven factories left as stubs, single
entity / single use case, and aggregator wiring (core-api/root,
apps/web-next bindAll) is left as a manual checklist.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

turbo/generators/templates/feature/src/__contracts__/entity-repository.contract.ts.hbs

@@ -0,0 +1,55 @@
+import { it, expect, beforeEach, describe } from "vitest";
+import { defineContractSuite } from "@repo/core-testing/contract";
+import type { I{{pascalCase entity}}Repository } from "../application/repositories/{{kebabCase entity}}.repository.interface.js";
+import type { {{pascalCase entity}} } from "../entities/models/{{kebabCase entity}}.js";
+
+/**
+ * Known fixtures every implementation's `buildSubject` must pre-seed.
+ * Exported so test files can pass them to `Mock{{pascalCase entity}}Repository` or the
+ * Payload stub without duplicating definitions.
+ */
+export const CONTRACT_{{constantCase entity}}_SEED: ReadonlyArray<readonly [string, {{pascalCase entity}}]> = [
+  ["seed-1", { id: "seed-1", name: "Seed One" }],
+  ["seed-2", { id: "seed-2", name: "Seed Two" }],
+];
+
+/**
+ * Contract for I{{pascalCase entity}}Repository.
+ *
+ * The interface exposes only `get{{pascalCase entity}}(id)`. The contract verifies
+ * found vs missing behaviour and span emission.
+ */
+export const {{camelCase entity}}RepositoryContract = defineContractSuite<I{{pascalCase entity}}Repository>(
+  "I{{pascalCase entity}}Repository",
+  ({ buildSubject, getTracer }) => {
+    let repo: I{{pascalCase entity}}Repository;
+
+    beforeEach(async () => {
+      repo = await buildSubject();
+    });
+
+    it("get{{pascalCase entity}} returns the seeded {{camelCase entity}} when id exists", async () => {
+      const result = await repo.get{{pascalCase entity}}("seed-1");
+      expect(result).not.toBeNull();
+      expect(result?.id).toBe("seed-1");
+      expect(typeof result?.name).toBe("string");
+    });
+
+    it("get{{pascalCase entity}} returns null for an unknown id", async () => {
+      const result = await repo.get{{pascalCase entity}}("does-not-exist");
+      expect(result).toBeNull();
+    });
+
+    describe("span emission", () => {
+      it("get{{pascalCase entity}} emits span '{{camelCase entity}}.get{{pascalCase entity}}' with op=repository", async () => {
+        if (!getTracer) return;
+        const tracer = getTracer();
+        tracer.reset();
+        await repo.get{{pascalCase entity}}("seed-1");
+        const span = tracer.findSpan("{{camelCase entity}}.get{{pascalCase entity}}");
+        expect(span).toBeDefined();
+        expect(span!.op).toBe("repository");
+      });
+    });
+  },
+);