refactor(cli): address review findings in telemetry code

- Extract shared isDevMode() to utils/env.ts (was duplicated in dev.ts and client.ts)
- Use ui/colors.ts instead of raw ANSI escapes in telemetry notice (respects NO_COLOR)
- Derive known commands from subCommands object instead of maintaining duplicate set
- Skip telemetry on --help/--version and unknown commands
- Gate incrementCommandCount() behind shouldTrack() (no disk writes in CI)
- Add flushSync() for process.exit() paths (beforeExit doesn't fire on explicit exit)
- Remove dead trackBrowserInstall(success) param (failure path never called it)
- Remove redundant isEnabled/anonymousId caching in client.ts (config.ts cache suffices)

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

packages/cli/src/telemetry/index.ts

@@ -1,5 +1,5 @@
 export { readConfig, writeConfig, incrementCommandCount, CONFIG_PATH } from "./config.js";
-export { trackEvent, flush, showTelemetryNotice } from "./client.js";
+export { trackEvent, flush, flushSync, shouldTrack, showTelemetryNotice } from "./client.js";
 export {
   trackCommand,
   trackRenderComplete,