feat(#166): Implement Stitcher module structure

Created the mosaic-stitcher module - the workflow orchestration layer
that wraps OpenClaw.

Responsibilities:
- Receive webhooks from @mosaic bot
- Apply Guard Rails (capability permissions)
- Apply Quality Rails (mandatory gates)
- Track all job steps and events
- Dispatch work to OpenClaw with constraints

Implementation:
- StitcherModule: Module definition with PrismaModule and BullMqModule
- StitcherService: Core orchestration logic
  - handleWebhook(): Process webhooks from @mosaic bot
  - dispatchJob(): Create RunnerJob and dispatch to BullMQ queue
  - applyGuardRails(): Check capability permissions for agent profiles
  - applyQualityRails(): Determine mandatory gates for job types
  - trackJobEvent(): Log events to database for audit trail
- StitcherController: HTTP endpoints
  - POST /stitcher/webhook: Webhook receiver
  - POST /stitcher/dispatch: Manual job dispatch
- DTOs and interfaces for type safety

TDD Process:
1. RED: Created failing tests (12 tests)
2. GREEN: Implemented minimal code to pass tests
3. REFACTOR: Fixed TypeScript strict mode issues

Quality Gates: ALL PASS
- Typecheck: PASS
- Lint: PASS
- Build: PASS
- Tests: PASS (12/12)

Token estimate: ~56,000 tokens

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/stitcher/stitcher.module.ts

@@ -0,0 +1,19 @@
+import { Module } from "@nestjs/common";
+import { StitcherController } from "./stitcher.controller";
+import { StitcherService } from "./stitcher.service";
+import { PrismaModule } from "../prisma/prisma.module";
+import { BullMqModule } from "../bullmq/bullmq.module";
+
+/**
+ * StitcherModule - Workflow orchestration module
+ *
+ * Provides the control layer that wraps OpenClaw for workflow execution.
+ * Handles webhooks, applies guard/quality rails, and dispatches jobs to queues.
+ */
+@Module({
+  imports: [PrismaModule, BullMqModule],
+  controllers: [StitcherController],
+  providers: [StitcherService],
+  exports: [StitcherService],
+})
+export class StitcherModule {}