#10723: fix(cli): filter empty flags in PowerShell completion generation

## Summary - Same issue as the bash completion fix — `option.flags.split(" ")[0]` can produce empty strings when flags have leading spaces or unusual formatting - This adds `.filter(Boolean)` to the PowerShell completion generator to skip empty flag entries, matching the fix already applied to the bash generator ## Test plan - [x] Verified the generated PowerShell script produces valid completion arrays without empty entries - [x] Existing tests pass Generated with [Claude Code](https://claude.com/claude-code) <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> - Updates PowerShell completion generation to avoid emitting empty flag entries when parsing `commander` option flags. - The root-level `$completions` array now maps option flags, filters out falsy values, then quotes them for PowerShell. - This aligns PowerShell completion behavior with the existing bash completion fix for similarly formatted `Option.flags` strings. <h3>Confidence Score: 5/5</h3> - This PR is safe to merge with minimal risk. - Change is narrowly scoped to PowerShell completion generation and only filters out empty flag strings before emitting the completion array; no broader logic, parsing, or I/O behavior changes. - src/cli/completion-cli.ts <!-- greptile_other_comments_section --> <!-- /greptile_comment -->