feat(#172): Implement Herald status updates

Implements status broadcasting via bridge module to chat channels. The Herald
service subscribes to job events and broadcasts status updates to Discord threads
using PDA-friendly language.

Features:
- Herald module with HeraldService for status broadcasting
- Subscribe to job lifecycle, step lifecycle, and gate events
- Format messages with PDA-friendly language (no "FAILED", "URGENT", etc.)
- Visual indicators for quick scanning (🟢, 🔵, ✅, ⚠️, ⏸️)
- Channel selection logic via workspace settings
- Route to Discord threads based on job metadata
- Comprehensive unit tests (14 tests passing, 85%+ coverage)

Message format examples:
- Job created: 🟢 Job created for #42
- Job started: 🔵 Job started for #42
- Job completed: ✅ Job completed for #42 (120s)
- Job failed: ⚠️ Job encountered an issue for #42
- Gate passed: ✅ Gate passed: build
- Gate failed: ⚠️ Gate needs attention: test

Quality gates: ✅ typecheck, lint, test, build

PR comment support deferred - requires GitHub/Gitea API client implementation.

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

apps/api/src/job-steps/job-steps.service.ts

@@ -145,4 +145,87 @@ export class JobStepsService {
       },
     });
   }
+
+  /**
+   * Start a step - simplified API without jobId
+   */
+  async start(id: string): Promise<Awaited<ReturnType<typeof this.prisma.jobStep.update>>> {
+    const step = await this.prisma.jobStep.findUnique({
+      where: { id },
+    });
+
+    if (!step) {
+      throw new NotFoundException(`JobStep with ID ${id} not found`);
+    }
+
+    return this.startStep(id, step.jobId);
+  }
+
+  /**
+   * Complete a step - simplified API without jobId
+   */
+  async complete(
+    id: string,
+    data?: { output?: string; tokensInput?: number; tokensOutput?: number }
+  ): Promise<Awaited<ReturnType<typeof this.prisma.jobStep.update>>> {
+    const step = await this.prisma.jobStep.findUnique({
+      where: { id },
+    });
+
+    if (!step) {
+      throw new NotFoundException(`JobStep with ID ${id} not found`);
+    }
+
+    const existingStep = await this.findOne(id, step.jobId);
+    const completedAt = new Date();
+    const durationMs = existingStep.startedAt
+      ? completedAt.getTime() - existingStep.startedAt.getTime()
+      : null;
+
+    const updateData: Prisma.JobStepUpdateInput = {
+      status: JobStepStatus.COMPLETED,
+      completedAt,
+      durationMs,
+    };
+
+    if (data?.output !== undefined) {
+      updateData.output = data.output;
+    }
+    if (data?.tokensInput !== undefined) {
+      updateData.tokensInput = data.tokensInput;
+    }
+    if (data?.tokensOutput !== undefined) {
+      updateData.tokensOutput = data.tokensOutput;
+    }
+
+    return this.prisma.jobStep.update({
+      where: { id, jobId: step.jobId },
+      data: updateData,
+    });
+  }
+
+  /**
+   * Fail a step - simplified API without jobId
+   */
+  async fail(
+    id: string,
+    data?: { error?: string }
+  ): Promise<Awaited<ReturnType<typeof this.prisma.jobStep.update>>> {
+    const step = await this.prisma.jobStep.findUnique({
+      where: { id },
+    });
+
+    if (!step) {
+      throw new NotFoundException(`JobStep with ID ${id} not found`);
+    }
+
+    return this.failStep(id, step.jobId, data?.error ?? "Step failed");
+  }
+
+  /**
+   * Get steps by job - alias for findAllByJob
+   */
+  async findByJob(jobId: string): Promise<Awaited<ReturnType<typeof this.findAllByJob>>> {
+    return this.findAllByJob(jobId);
+  }
 }