fix: address Phase 1 code-quality review findings

- Generator feature templates emit ctx-arg signatures + updated checklist
- signUpUseCase test for bus=undefined path
- di-explainer.html: bind-dev-seed no-arg → ctx
- data-flow-explainer.html: tradeoff card → ctx
- BindContextBase no longer exported
- CLAUDE.md binder bullet: drop vestigial cast guidance

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

turbo/generators/config.ts

@@ -303,8 +303,8 @@ export default function generator(plop: PlopTypes.NodePlopAPI): void {
           `  2. apps/web-next/src/server/bind-production.ts:`,
           `     - import { bindProduction${cap(a.name)} } from "${pkg}/di/bind-production";`,
           `     - import { bindDevSeed${cap(a.name)} } from "${pkg}/di/bind-dev-seed";`,
-          `     - call bindProduction${cap(a.name)}(config, tracer, logger) (production branch)`,
-          `     - call await bindDevSeed${cap(a.name)}(tracer, logger) (dev-seed branch)`,
+          `     - call bindProduction${cap(a.name)}(ctx) (production branch, ctx: BindProductionContext)`,
+          `     - call await bindDevSeed${cap(a.name)}(ctx) (dev-seed branch, ctx: BindContext)`,
           "",
           `  3. packages/core-api/src/root.ts:`,
           `     - import { ${camel(a.name)}Router } from "${pkg}/api";`,