docs: update progress tracking for Epic 5.1 completion

Mark Epic 5.1 (Currency value object) as complete.
Epic 5 (Economy and Inventory) is now 1/6 tasks complete.

Refs #40

Author: martincjarvis

docs/plans/rules-engine-design.md

@@ -18,24 +18,25 @@ Epic 4 (Crafting and Class Progression) complete! Next: Epic 5 (Economy and Inve
 
 ### Epic Status Overview
 
-| Epic | Title                            | Status      | Progress | GitHub Issue |
-| ---- | -------------------------------- | ----------- | -------- | ------------ |
-| 1    | Project Foundation               | ✅ Complete | 5/5      | #3           |
-| 2    | Time and Simulation Loop         | ✅ Complete | 6/6      | #4           |
-| 3    | NPC Decision Making              | ✅ Complete | 6/6      | #5           |
-| 4    | Crafting and Class Progression   | ✅ Complete | 8/8      | #6           |
-| 5    | Economy and Inventory            | ⏳ Planned  | 0/6      | #7           |
+| Epic | Title                            | Status         | Progress | GitHub Issue |
+| ---- | -------------------------------- | -------------- | -------- | ------------ |
+| 1    | Project Foundation               | ✅ Complete    | 5/5      | #3           |
+| 2    | Time and Simulation Loop         | ✅ Complete    | 6/6      | #4           |
+| 3    | NPC Decision Making              | ✅ Complete    | 6/6      | #5           |
+| 4    | Crafting and Class Progression   | ✅ Complete    | 8/8      | #6           |
+| 5    | Economy and Inventory            | 🔄 In Progress | 1/6      | #7           |
 | 6    | Contracts and Commitments        | 🔄 Partial  | 2/6      | #8           |
 | 7    | Settlement and Guild             | ⏳ Planned  | 0/6      | #9           |
 | 8    | Scenario Testing Framework       | ⏳ Planned  | 0/7      | #10          |
 | 9    | Persistence                      | ⏳ Planned  | 0/4      | #11          |
 | 10   | Apprenticeship and Role Stacking | ⏳ Planned  | 0/4      | #12          |
 | 11   | Full Progression Scenario        | ⏳ Planned  | 0/5      | #13          |
 
-**Total Progress**: 27/58 tasks complete (47%)
+**Total Progress**: 28/58 tasks complete (48%)
 
 ### Recent Completions
 
+- ✅ **2026-01-19**: Epic 5.1 - Currency value object (#40, PR #139 - awaiting review)
 - ✅ **2026-01-19**: Epic 4.8 - Masterwork → Master rank trigger (#39, PR #136)
 - ✅ **2026-01-19**: Epic 4.7 - CraftingSystem (#38, PR #135)
 - ✅ **2026-01-19**: Epic 4.6 - CraftingOutcomeRule (#37, PR #134)
@@ -49,8 +50,9 @@ Epic 4 (Crafting and Class Progression) complete! Next: Epic 5 (Economy and Inve
 
 Priority order for remaining work:
 
-1. **Epic 5** - #7: Economy and Inventory (0/6 tasks)
-2. **Epic 6** - #8: Complete Contracts and Commitments (4/6 remaining)
+1. **Epic 5.2** - #41: Implement InventoryComponent
+2. **Epic 5** - #7: Complete Economy and Inventory (5/6 remaining)
+3. **Epic 6** - #8: Complete Contracts and Commitments (4/6 remaining)
 
 ## Key Design Decisions
 
@@ -262,11 +264,23 @@ _For implementation patterns, examine referenced code paths._
 
 ---
 
+## Epic 5: Economy and Inventory (🔄 1/6 tasks)
+
+**5.1 Implement Currency value object** ✅ _Issue #40, PR #139 (awaiting review)_
+
+- ✅ FromSilver(), FromGold(), FromMixed() factory methods
+- ✅ Silver and Gold properties for denomination access
+- ✅ ToBreakdown() for converting to (gold, silver, copper) tuple
+- ✅ Conversion rates: 1 silver = 10 copper, 1 gold = 100 copper
+- **Verified**: 6 tests pass, all 517 tests pass
+
+---
+
 ### Planned Epics
 
 | Epic | Title                            | Status | Issue | Key Components                                |
 | ---- | -------------------------------- | ------ | ----- | --------------------------------------------- |
-| 5    | Economy and Inventory            | ⏳ 0/6 | #7    | Currency, InventoryComponent, PriceCalculator |
+| 5    | Economy and Inventory            | 🔄 1/6 | #7    | Currency, InventoryComponent, PriceCalculator |
 | 6    | Contracts and Commitments        | 🔄 2/6 | #8    | Commitment types, ContractActions             |
 | 7    | Settlement and Guild             | ⏳ 0/6 | #9    | Settlement, Guild, leadership                 |
 | 8    | Scenario Testing Framework       | ⏳ 0/7 | #10   | WorldBuilder, CharacterBuilder                |