docs(gitignore): document cli-with-sentry dist exclusion

Add comment explaining that packages/cli-with-sentry/dist/ is
gitignored as ephemeral esbuild output, consistent with the
packages/cli/dist/ pattern.

The root .gitignore already has comprehensive patterns:
- **/build (workspace + archive)
- **/coverage (test coverage)
- **/html (generated docs)
- **/dist is NOT global because dist/ contains blessed releases

Individual packages use local .gitignore files to exclude their
ephemeral dist/ output (CLI packages) while allowing tracked dist/
in other packages (binary releases, WASM artifacts, models).

Author: jdalton

.gitignore

@@ -43,6 +43,7 @@ Thumbs.db
 # Build artifacts: build/ = gitignored (workspace + archive), dist/ = tracked (blessed releases).
 # Exceptions:
 #   - packages/cli/dist/ is Rollup output (ephemeral), gitignored by packages/cli/.gitignore
+#   - packages/cli-with-sentry/dist/ is esbuild output (ephemeral), gitignored by packages/cli-with-sentry/.gitignore
 #   - !/docs/build allows tracking docs/build/ (documentation directory, not build artifacts)
 #   - Note: New files in docs/build/ require `git add -f` due to **/build pattern