types: cleanup bitfields implementation (leanEthereum#50)

* types: cleanup bitfields implementation

* better doc

* some doc fixes

* make justified_slots a bitlist

* make justifications_validators a bitlist

* linter fix

Author: tcoratger

src/lean_spec/subspecs/containers/state.py

@@ -10,6 +10,7 @@
 from lean_spec.subspecs.ssz.hash import hash_tree_root
 from lean_spec.types import Boolean, Bytes32, Container, Uint64, ValidatorIndex
 from lean_spec.types import List as SSZList
+from lean_spec.types.bitfields import Bitlist
 
 from .block import Block, BlockBody, BlockHeader, SignedBlock
 from .checkpoint import Checkpoint
@@ -43,17 +44,16 @@ class State(Container):
     historical_block_hashes: SSZList[Bytes32, DEVNET_CONFIG.historical_roots_limit.as_int()]  # type: ignore
     """A list of historical block root hashes."""
 
-    justified_slots: SSZList[Boolean, DEVNET_CONFIG.historical_roots_limit.as_int()]  # type: ignore
+    justified_slots: Bitlist[DEVNET_CONFIG.historical_roots_limit.as_int()]  # type: ignore
     """A bitfield indicating which historical slots were justified."""
 
     # Justification tracking (flattened for SSZ compatibility)
     justifications_roots: SSZList[Bytes32, DEVNET_CONFIG.historical_roots_limit.as_int()]  # type: ignore
     """Roots of justified blocks."""
 
-    justifications_validators: SSZList[  # type: ignore
-        Boolean,
+    justifications_validators: Bitlist[  # type: ignore[valid-type, type-arg]
         DEVNET_CONFIG.historical_roots_limit.as_int()
-        * DEVNET_CONFIG.historical_roots_limit.as_int(),
+        * DEVNET_CONFIG.historical_roots_limit.as_int()
     ]
     """A bitlist of validators who participated in justifications."""