feat(CORE-001D): close remaining boundary cleanup slices

docs/roadmap/done/CORE-001D-decimal-boundary-cleanup.yaml

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+id: CORE-001D
+title: External Boundary and Persistence Cleanup for Decimal Unit Types
+status: done
+priority: P2
+effort: M
+depends_on:
+  - CORE-001B
+  - CORE-001C
+tags:
+  - core
+  - decimal
+  - persistence
+summary: The remaining Decimal/unit-safe boundary cleanup slices have been completed across persistence, provider/cache adapters, alerts/settings, historical-provider boundaries, and historical scenario service entrypoints.
+completed_notes:
+  - `CORE-001D1` made the portfolio/workspace persistence seam explicit with strict unit-aware schema validation and atomic saves.
+  - `CORE-001D2A` and `CORE-001D2B` normalized quote, option-expiration, and options-chain provider/cache boundaries in `DataService`.
+  - `CORE-001D2C` normalized `PriceFeed` cache/provider payloads through explicit adapters aligned with `CacheService`.
+  - `CORE-001D2D` normalized historical provider rows and synthetic option quote construction in `app/services/backtesting/historical_provider.py`.
+  - `CORE-001D3A` tightened alerts and settings save-status service entrypoints with named normalization adapters.
+  - `CORE-001D3B` turned corrupt alert-history storage into an explicit degraded state with logging and route-visible notices.
+  - `CORE-001D3C` normalized historical scenario inputs for backtests and event comparison through a shared adapter.
+  - Remaining raw-float dataclasses such as `LombardPortfolio`, `PriceData`, and MVP backtest result models are now treated as intentional edge-facing compatibility surfaces rather than undocumented internal seams.
+  - Validated through focused pytest coverage, browser-driven local Docker checks on the affected routes, and repeated `make build` runs across the shipped slices.