docs(12): create phase plan

.planning/ROADMAP.md

@@ -83,7 +83,9 @@ Plans:
   2. The lightest candidate column is highlighted and all other columns show their weight difference relative to it; the cheapest candidate is highlighted similarly for price
   3. The comparison table scrolls horizontally on a narrow viewport without breaking layout; the attribute label column stays fixed on the left
   4. A resolved thread shows the comparison table in read-only mode with the winning candidate visually marked
-**Plans**: TBD
+**Plans:** 1 plan
+Plans:
+- [ ] 12-01-PLAN.md — ComparisonTable component + compare toggle wiring in thread detail
 
 ### Phase 13: Setup Impact Preview
 **Goal**: Users can select any setup and see exactly how much weight and cost each candidate would add or subtract
@@ -111,5 +113,5 @@ Plans:
 | 9. Weight Classification and Visualization | v1.2 | 2/2 | Complete | 2026-03-16 |
 | 10. Schema Foundation + Pros/Cons Fields | v1.3 | 1/1 | Complete | 2026-03-16 |
 | 11. Candidate Ranking | 2/2 | Complete    | 2026-03-16 | - |
-| 12. Comparison View | v1.3 | 0/TBD | Not started | - |
+| 12. Comparison View | v1.3 | 0/1 | Not started | - |
 | 13. Setup Impact Preview | v1.3 | 0/TBD | Not started | - |