docs: mark DISPLAY-001 and DISPLAY-002 done, update roadmap

docs/roadmap/done/DISPLAY-001-underlying-mode-switching.yaml

@@ -0,0 +1,31 @@
+id: DISPLAY-001
+title: Underlying Mode Switching
+status: backlog
+priority: P0
+size: M
+depends_on:
+  - PORTFOLIO-001
+  - DATA-004
+tags: [ui, display-mode]
+summary: Allow the entire app to switch between GLD, GC=F, and XAU display modes.
+acceptance_criteria:
+  - Settings page has "Display Mode" selector: GLD shares, Gold Ounces, Gold Grams, GC=F contracts
+  - In GLD mode: GLD positions show direct values, other positions converted using entry-date GLD backing
+  - In Gold mode: All positions converted to equivalent oz/g using entry-date conversions
+  - In GC=F mode: GC=F positions show direct values, others converted
+  - Overview shows collateral in display mode units
+  - Hedge page shows protection in display mode units
+  - Backtests show results in display mode units
+  - Mode persists per workspace
+notes:
+  - Conversion uses GLD_ounces_per_share(entry_date) for historical accuracy
+  - GC=F contract size is fixed at 100 oz
+  - XAU grams to oz conversion: 31.1035 g/oz
+  - Mode switching is a display concern, not a data concern
+  - Position data remains in original units
+implementation_hints:
+  - Add `display_mode: "GLD" | "XAU_OZ" | "XAU_G" | "GCF"` to `PortfolioConfig`
+  - Add `convert_to_display(position, display_mode, reference_date)` in `app/domain/conversions.py`
+  - Reuse existing `gld_ounces_per_share(date)` for historical conversion
+  - Overview/hedge/backtests use display conversion layer
+  - Settings page saves display_mode preference