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/vitest.config.ts.hbs

@@ -0,0 +1,47 @@
+import path from "node:path";
+import { mergeConfig } from "vitest/config";
+import { nodeVitestConfig } from "@repo/core-typescript/vitest.base.node";
+
+export default mergeConfig(nodeVitestConfig, {
+  test: {
+    coverage: {
+      exclude: [
+        // DI bootstrap — wires InversifyJS at app startup; not unit-testable
+        "src/di/bind-production.ts",
+        // Pure TypeScript interface files — not executable
+        "src/application/repositories/**",
+        // Payload CMS templates — declarative data, tested via integration
+        "src/integrations/cms/**",
+        // React Query option builders — integration-tested in apps
+        "src/ui/**",
+      ],
+      thresholds: {
+        "src/entities/**": {
+          statements: 100,
+          branches: 100,
+          functions: 100,
+          lines: 100,
+        },
+        "src/application/use-cases/**": {
+          statements: 100,
+          branches: 95,
+          functions: 100,
+          lines: 100,
+        },
+        "src/interface-adapters/controllers/**": {
+          statements: 100,
+          branches: 95,
+          functions: 100,
+          lines: 100,
+        },
+        statements: 80,
+        branches: 75,
+        functions: 80,
+        lines: 80,
+      },
+    },
+  },
+  resolve: {
+    alias: { "@": path.resolve(__dirname, "./src") },
+  },
+});