FN-8065: preview plans before refinement questions

Show a read-only plan preview at the Planning Mode deepening checkpoint.

- Persist pending plan details on the checkpoint question for fresh and restored sessions.
- Render formatted plan content and deliverables above refinement choices.
- Cover preview behavior and document the checkpoint flow.

Files changed:
 .../fn-8065-planning-checkpoint-plan-preview.md    |  7 +++
 docs/dashboard-guide.md                            |  3 +-
 packages/core/src/types.ts                         | 11 ++++
 .../dashboard/app/components/PlanningModeModal.css | 60 ++++++++++++++++++++++
 .../dashboard/app/components/PlanningModeModal.tsx | 44 ++++++++++++++++
 .../PlanningModeModal.planning-flow.test.tsx       | 24 ++++++++-
 .../planning-interview-formatters.test.ts          | 19 +++++++
 packages/dashboard/src/planning.ts                 | 10 ++++
 8 files changed, 175 insertions(+), 3 deletions(-)

Fusion-Task-Id: FN-8065

Fusion-Task-Lineage: 13cd52c3-af82-4723-a6b1-3366775213e1

Co-authored-by: Fusion (runfusion.ai) <noreply@runfusion.ai>

docs/dashboard-guide.md

@@ -468,8 +468,9 @@ Use **Copy prompt** in the error panel or an active interview question to copy t
 
 <!-- FNXC:PlanningModeDeepeningCheckpoint 2026-07-02-12:18: Planning Mode must pause before every final summary at a mandatory "Would you like to go deeper?" checkpoint so users can request inferred follow-up themes, enter a custom topic, or proceed without deepening. -->
 <!-- FNXC:PlanningMode 2026-07-05-00:25: The planning AI now proposes plan-specific deepening themes (deepeningThemes on the completion payload) so this checkpoint surfaces topics tailored to the user's actual plan, including angles they had not anticipated, instead of a fixed generic set. The regex-derived generic themes remain the fallback whenever the AI supplies none (FN-7616 / issue #1912). -->
+<!-- FNXC:PlanningMode 2026-07-16-00:00: FN-8065 / GitHub #2150 requires the deepening checkpoint to show the generated plan read-only above its refinement choices, so users can review the title, Markdown description, and deliverables before proceeding. -->
 
-Before Planning Mode shows **Planning Complete!** or the final plan summary, it first asks **Would you like to go deeper?**. The suggested themes are plan-specific: the planning AI proposes topics tailored to your plan's title, description, and deliverables as part of its completion response, surfacing angles you may not have anticipated. When the AI does not supply any themes, Planning Mode falls back to a generic, regex-derived set (scope, edge cases, UX, dependencies, testing, rollout) inferred from the interview text. Either way, select one or more suggested themes to continue the interview, use **Other** to add a custom topic, or choose **No, continue to final summary** to reveal the pending summary and task-creation actions.
+Before Planning Mode shows **Planning Complete!** or the final plan summary, it first asks **Would you like to go deeper?**. A read-only preview of the generated plan appears above the refinement options so you can review its title, formatted description, and key deliverables before deciding. The suggested themes are plan-specific: the planning AI proposes topics tailored to your plan's title, description, and deliverables as part of its completion response, surfacing angles you may not have anticipated. When the AI does not supply any themes, Planning Mode falls back to a generic, regex-derived set (scope, edge cases, UX, dependencies, testing, rollout) inferred from the interview text. Either way, select one or more suggested themes to continue the interview, use **Other** to add a custom topic, or choose **Proceed to final plan** to reveal the pending summary and task-creation actions.
 
 - **Branch strategy** options mirror Subtask Breakdown semantics:
   - `Use project/default branch`