Add AttachedDeviceEntry and DeviceCapacityEntry models with legacy-map projection

Add typed entry models for kernel attached devices under manager/data/kernel/types.py, following the ResourceSlotEntry precedent (common/types.py): a list-friendly typed form of a legacy map-shaped structure with a projection helper.

Scope:
- DeviceCapacityEntry: name (open key set: smp, mem, cores, ...) + value as a decimal string (ResourceSlotEntry.quantity precedent). Values are constrained to numerics per the declared ComputedDeviceCapacity contract; non-numeric values are handled leniently (skipped or stringified) without raising.
- AttachedDeviceEntry: device_name (top-level map key such as cuda or cpu), device_id, model_name, capacities (list of DeviceCapacityEntry projected from the raw data map).
- Projection classmethod from_attached_devices(raw) that flattens the legacy nested shape (device_name to list of DeviceModelInfo) into a flat entry list; entries without device_id are skipped.
- KernelCreationInfo.get_attached_devices() in data/sokovan/lifecycle.py returning the entry list, following the get_resource_allocations precedent.

No reverse converter (entries back to the legacy map) is needed: the dual-write path keeps writing the original payload as-is.

Success Criteria
- [ ] projecting a cuda-shaped payload (smp, mem) yields entries with capacities named smp and mem
- [ ] projecting a cpu-shaped payload (cores) and an empty data map both work
- [ ] non-numeric capacity values are handled leniently without raising
- [ ] device entries missing device_id are skipped
- [ ] pants test passes for affected packages

JIRA Issue: BA-7177

Start with manager/data/kernel/types.py and compare ResourceSlotEntry in common/types.py, then inspect KernelCreationInfo.get_resource_allocations() in data/sokovan/lifecycle.py. Use the stated CUDA, CPU, empty-map, non-numeric, and missing-device_id cases to guide the projection behavior, and run pants tests for the affected packages to verify completion.

Written by the indexing model from the issue text.