chore: add CI, coverage gates, and fix template hygiene

Wires the previously-inert @vitest/coverage-v8 into the test builder with
measured thresholds, adds a GitHub Actions workflow (format, test, build),
and fixes assorted gaps a cloning team would hit: no LICENSE, no engines/
.nvmrc, an unusable prettier install, a committed local-only settings file,
a dead 0-byte stylesheet, and a broken Karma-era VS Code test/debug config.
Also drops @angular/forms, which nothing in src/ imports.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

.gitignore

@@ -39,6 +39,11 @@ testem.log
 /typings
 __screenshots__/
 
+# Local secrets / machine-local settings
+.env
+.env.*
+.claude/settings.local.json
+
 # System files
 .DS_Store
 Thumbs.db