chore: adopt remote dprint config, tidy examples

Extend dprint from a shared remote config and add the prettier
and exec plugins, formatting TOML via a new tombi.toml instead
of golangci-lint fmt. Taskfile.yml, scripts/build.sh, and
html_styles.css pick up the resulting reformat.

Exporter examples now write to a temp dir and clean up after
themselves instead of leaving output.md/.docx/.html in the
repo. Drop the stray internal/exporters/output.docx and ignore
internal/exporters/output.* going forward.

.gitignore

@@ -34,6 +34,8 @@ output/
 outputs/
 articulate-sample.json
 test-output.*
+# Example test exports (defensive; tests now write to a temp dir)
+internal/exporters/output.*
 go-os-arch-matrix.csv
 test_godocx.go
 test_input.json