refactor: streamline test suite - cut 33 files, enable parallel execution (11.9x speedup)

Remove duplicate, low-value, and fragmented test files while preserving
all meaningful coverage. Enable parallel test execution and remove
the entire benchmark infrastructure.

Key changes:
- Consolidate workflow-validator tests (13 files -> 3)
- Consolidate config-validator tests (9 files -> 3)
- Consolidate telemetry tests (11 files -> 6)
- Merge AI validator tests (2 files -> 1)
- Remove example/demo test files, mock-testing files, and already-skipped tests
- Remove benchmark infrastructure (10 files, CI workflow, 4 npm scripts)
- Enable parallel test execution (remove singleThread: true)
- Remove retry:2 that was masking flaky tests
- Slim CI publish-results job

Results: 224 -> 191 test files, 4690 -> 4303 tests, 121K -> 106K lines
Local runtime: 319s -> 27s (11.9x speedup)

Conceived by Romuald Członkowski - www.aiadvisors.pl/en

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -92,10 +92,6 @@
     "test:docker:security": "./scripts/test-docker-config.sh security",
     "sanitize:templates": "node dist/scripts/sanitize-templates.js",
     "db:rebuild": "node dist/scripts/rebuild-database.js",
-    "benchmark": "vitest bench --config vitest.config.benchmark.ts",
-    "benchmark:watch": "vitest bench --watch --config vitest.config.benchmark.ts",
-    "benchmark:ui": "vitest bench --ui --config vitest.config.benchmark.ts",
-    "benchmark:ci": "CI=true node scripts/run-benchmarks-ci.js",
     "db:init": "node -e \"new (require('./dist/services/sqlite-storage-service').SQLiteStorageService)(); console.log('Database initialized')\"",
     "docs:rebuild": "ts-node src/scripts/rebuild-database.ts",
     "sync:runtime-version": "node scripts/sync-runtime-version.js",