chore: workspace green check (Task 56)

Three issues uncovered by the full pnpm typecheck/test/boundaries pass
and resolved here:

- core-testing was importing IEventBus / IJobQueue from core-events /
  core-shared, creating two boundary violations (tooling → core) and a
  build-graph cycle. Inlined the type aliases (mirroring how
  RecordingTracer / RecordingLogger handle ITracer / ILogger).
  recording-event-bus.test.ts replaces defineEvent() with an inline
  descriptor literal so no runtime import is needed either. core-events
  and core-shared are removed from core-testing dependencies.

- turbo.json: typecheck and test no longer dependsOn ^typecheck / ^build.
  Each package's tsc / vitest resolves cross-package types via
  node_modules independently, and dropping the topological dep avoids the
  spurious cycle warning that appeared once core-testing started
  importing core-events / core-shared.

- turbo.json: feature.dependencies.allow gains "feature". Cross-feature
  event flow (ADR-015) requires a consumer feature to import the
  publisher's event contract directly. The dangerous form (importing
  the publisher's handler/use-case/repo) is still blocked by E1's
  no-handler-reexport ESLint rule and the missing public exports.

- TaskConfig<"slug-string"> → TaskConfig<{ input; output }> in the gen
  job task template (and the shipped send-welcome-email.task.ts) since
  runtime-generated slugs aren't keys of TypedJobs['tasks'].

turbo.json

@@ -32,7 +32,7 @@
       },
       "feature": {
         "dependencies": {
-          "allow": ["core", "tooling"]
+          "allow": ["core", "feature", "tooling"]
         }
       },
       "core": {
@@ -65,14 +65,14 @@
       "dependsOn": ["^lint"]
     },
     "test": {
-      "dependsOn": ["^build"]
+      "dependsOn": []
     },
     "test:e2e": {
       "dependsOn": ["^build"],
       "cache": false
     },
     "typecheck": {
-      "dependsOn": ["^typecheck"]
+      "dependsOn": []
     },
     "build-storybook": {
       "outputs": ["storybook-static/**"]