Remove legacy abstractions that are no longer used after the
100% blob storage model migration (#113):
- IdMappingPort trait from application/ports/outbound.rs
- storage_mediator.rs module (StorageMediator trait + impls)
- StorageMediator impl from PathService
- write_behind_cache.rs (FS-based, incompatible with blob model)
The WriteBehindCachePort trait and Optional fields in services
are preserved for potential future blob-compatible caching.
-968 lines of dead code removed. Build clean, RC=0.
Standardize code formatting across all 173 Rust source files
using rustfmt. No functional changes - purely cosmetic.
This establishes a consistent code style baseline for the
project going forward.
Dionisio