Adds --analyze flag to /gsd:discuss-phase that provides a trade-off
analysis before each question (or question group in --batch mode).
When active, each question is preceded by:
- 2-3 options with pros/cons based on codebase context
- A recommended approach with reasoning
- Known pitfalls or constraints from prior phases
Composable with existing flags: --batch --analyze gives grouped
questions each with trade-off tables.
Closes#833
be302f02bb