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/__seeds__/dev.ts.hbs

@@ -0,0 +1,16 @@
+import type { {{pascalCase entity}} } from "../entities/models/{{kebabCase entity}}.js";
+
+/**
+ * Realistic dev seed for `bindDevSeed{{pascalCase name}}`.
+ *
+ * Phase-1: returns a small hand-rolled Map. Replace with a faker-driven
+ * `defineFactory` (see `packages/blog/src/__factories__/`) once the entity
+ * shape stabilises.
+ */
+export function buildDev{{pascalCase entity}}Map(): Map<string, {{pascalCase entity}}> {
+  return new Map<string, {{pascalCase entity}}>([
+    ["dev-1", { id: "dev-1", name: "Dev One" }],
+    ["dev-2", { id: "dev-2", name: "Dev Two" }],
+    ["dev-3", { id: "dev-3", name: "Dev Three" }],
+  ]);
+}