feat(core-events): scaffold events optional core

Scaffolded via pnpm turbo gen core-package events (generator-first,
ADR-022 pre-shipped zod trace landed in docs/library-decisions/).
Generator wired transpilePackages + E1/J eslint rule block. Two
story-00-precedent additions so the coverage gates pass: the
@vitest/coverage-v8 devDep (L0 sweep) and the honest symbols.ts
exclude (mirroring core-shared/vitest.config.ts) plus its missing
ALLOWED_GLOBS mirror in scripts/coverage/diff.mjs (L1 gate). No
consumers wired — compile-green floor for the walking-skeleton
PRD (ADR-027).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016j8z4VHjedXDTjEDNg7qHK

scripts/coverage/diff.mjs

@@ -83,6 +83,10 @@ const ALLOWED_GLOBS = [
   /\.d\.ts$/, // ambient declaration files — no runtime code by definition
   /\.interface\.ts$/,
   /\/index\.ts$/, // barrel re-exports — no executable code
+  // DI symbol constants — boilerplate, covered implicitly by bind-* tests;
+  // mirrors the "src/**/symbols.ts" coverage exclude documented in
+  // core-shared/vitest.config.ts (and core-events/vitest.config.ts)
+  /\/symbols\.ts$/,
   // Build artifacts
   /\.tsbuildinfo$/,
   /\.lock$/,