#10710: fix(cli): filter empty flags in bash completion generation

## Summary - `options.flags.split(" ")[0]` can produce empty strings when an option has empty/whitespace-only flags - Empty tokens in the `opts` variable cause spurious bash completion matches - Add `.filter(Boolean)` at both top-level and subcommand levels ## Test plan - [x] Generated bash completion script no longer contains consecutive spaces from empty flags - [x] All existing tests pass Generated with [Claude Code](https://claude.com/claude-code) <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> - Updates bash completion generation to avoid emitting empty option tokens when an option’s `flags` string is empty/whitespace-only. - Applies `.filter(Boolean)` after mapping `Option.flags.split(" ")[0]` for both the root command and subcommands. - Resulting `opts` word list used by `compgen -W` no longer contains empty entries that create spurious matches in bash completion. - Change is localized to `src/cli/completion-cli.ts` and does not alter zsh/powershell/fish completion code paths. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - Change is narrowly scoped to bash completion generation and only filters out empty flag tokens; it preserves existing behavior for valid flags and avoids creating invalid completion candidates. - No files require special attention <!-- greptile_other_comments_section --> <!-- /greptile_comment -->