feat: phase 3 observability — IMS telemetry merge

Port IMS telemetry into Primora conventions:

- core.components/core.events (migration 00004 + sqlc) scoped to projects
- POST /api/v1/ingest — single or <=500-event batches via project prm_
  keys (X-Primora-Key alias), auto-registering components, permissive CORS
- Issues: fingerprint-grouped errors with count/severity/first+last seen
- Reads: events w/ filters + before-cursor, components, stats (1h/24h/7d/30d
  bucketed series + component health + totals + metric names), metric
  series (avg/p50/p95/max)
- GET .../telemetry/stream — project-scoped SSE through an in-process hub
  (buffered subs, drop-on-slow, 25s keepalives); ?api_key=/?token= auth
  for EventSource
- Telemetry page: health/issues/events/metrics/integrate tabs, live badge,
  390px-clean; demo stubs
- @primora/client SDK (createPrimoraClient: capture*/heartbeat/installAuto,
  queued keepalive flushes)
- MCP: primora_list_issues/list_events/telemetry_stats/metric_series
- IMS README deprecation note pointing here

Also fixes workspace pins to 0.3.0 — npm ci in the frontend image was
resolving the unpublished 0.2.0 spec from the registry.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/backend/internal/services/platform_service.go

@@ -32,6 +32,7 @@ type PlatformService struct {
 	publicURL      string
 	dbx            *dbx.Client
 	managedDBSeeds []ManagedDBSeed
+	hub            *EventHub
 }
 
 type BootstrapInput struct {
@@ -210,7 +211,7 @@ type InvitationSummary struct {
 }
 
 func NewPlatformService(repo *repositories.CoreRepository, store *storage.LocalStore, mailer *Mailer, publicURL string, dbxClient *dbx.Client, managedDBSeeds []ManagedDBSeed) *PlatformService {
-	return &PlatformService{repo: repo, store: store, mailer: mailer, publicURL: publicURL, dbx: dbxClient, managedDBSeeds: managedDBSeeds}
+	return &PlatformService{repo: repo, store: store, mailer: mailer, publicURL: publicURL, dbx: dbxClient, managedDBSeeds: managedDBSeeds, hub: NewEventHub()}
 }
 
 func (s *PlatformService) Me(ctx context.Context, actor *models.Actor) (PlatformSummary, error) {