[codex] fix root help usage contrast

[supersylar]

Summary

Fix the top-level dws --help Usage examples so the command text uses the terminal default foreground color instead of forcing bright white.

Context

A user reported that the Usage: examples in the root scaffold/help output were nearly invisible on a light terminal background. The selected-text screenshot confirmed that the text was present but rendered with very low contrast.

Root cause: renderRootHelp wrapped the two Usage example strings with tui.White(...), and tui.White maps to color.FgHiWhite. That emits bright-white ANSI (\x1b[97m), which is unreadable in light themes.

Screenshots:
Issue：

Fixed：

Change

• Remove tui.White(...) from the two top-level Usage example lines.
• Keep the existing colored bullet while leaving the command text as plain terminal text.

Validation

Passed:

• gofmt -w internal/app/root_help.go internal/app/visibility_test.go && git diff --check
• go test -count=1 ./internal/app -run 'TestRenderRootHelpIncludesLong|TestRootHelpDoesNotRequirePINOrLogin'
• go build -o /tmp/dws-root-help-contrast ./cmd
• Manual root help check with env -u NO_COLOR TERM=xterm-256color CLICOLOR_FORCE=1 /tmp/dws-root-help-contrast --help; the requester confirmed the output is readable.

Known unrelated failures observed while validating:

• make lint fails on existing staticcheck findings outside this change, including unused functions in internal/app/auth_command.go, internal/helpers/devapp.go, internal/helpers/devdoc.go, internal/helpers/wiki.go, internal/transport/diagnostics.go, plus SA4017 in internal/helpers/connect_daemon_test.go.
• make test fails in existing integration/script suites: auth required in integration/extensions, missing recovery temp file in integration/recovery, and tar archive format errors in test/scripts.