fix(#187): implement server-side SSE error recovery

Server-side improvements (ALL 27/27 TESTS PASSING):
- Add streamEventsFrom() method with lastEventId parameter for resuming streams
- Include event IDs in SSE messages (id: event-123) for reconnection support
- Send retry interval header (retry: 3000ms) to clients
- Classify errors as retryable vs non-retryable
- Handle transient errors gracefully with retry logic
- Support Last-Event-ID header in controller for automatic reconnection

Files modified:
- apps/api/src/runner-jobs/runner-jobs.service.ts (new streamEventsFrom method)
- apps/api/src/runner-jobs/runner-jobs.controller.ts (Last-Event-ID header support)
- apps/api/src/runner-jobs/runner-jobs.service.spec.ts (comprehensive error recovery tests)
- docs/scratchpads/187-implement-sse-error-recovery.md (implementation notes)

This ensures robust real-time updates with automatic recovery from network issues.
Client-side React hook will be added in a follow-up PR after fixing Quality Rails lint issues.

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

apps/api/src/runner-jobs/runner-jobs.controller.ts

@@ -1,4 +1,4 @@
-import { Controller, Get, Post, Body, Param, Query, UseGuards, Res } from "@nestjs/common";
+import { Controller, Get, Post, Body, Param, Query, UseGuards, Res, Headers } from "@nestjs/common";
 import { Response } from "express";
 import { RunnerJobsService } from "./runner-jobs.service";
 import { CreateJobDto, QueryJobsDto } from "./dto";
@@ -93,12 +93,14 @@ export class RunnerJobsController {
    * GET /api/runner-jobs/:id/events/stream
    * Stream job events via Server-Sent Events (SSE)
    * Requires: Any workspace member
+   * Supports automatic reconnection via Last-Event-ID header
    */
   @Get(":id/events/stream")
   @RequirePermission(Permission.WORKSPACE_ANY)
   async streamEvents(
     @Param("id") id: string,
     @Workspace() workspaceId: string,
+    @Headers("last-event-id") lastEventId: string | undefined,
     @Res() res: Response
   ): Promise<void> {
     // Set SSE headers
@@ -108,7 +110,7 @@ export class RunnerJobsController {
     res.setHeader("X-Accel-Buffering", "no"); // Disable nginx buffering
 
     try {
-      await this.runnerJobsService.streamEvents(id, workspaceId, res);
+      await this.runnerJobsService.streamEvents(id, workspaceId, res, lastEventId);
     } catch (error: unknown) {
       // Write error to stream
       const errorMessage = error instanceof Error ? error.message : String(error);