Hierarchical state diffs in hot DB (#6750)

This PR implements https://github.com/sigp/lighthouse/pull/5978 (tree-states) but on the hot DB. It allows Lighthouse to massively reduce its disk footprint during non-finality and overall I/O in all cases.

Closes https://github.com/sigp/lighthouse/issues/6580

Conga into https://github.com/sigp/lighthouse/pull/6744

### TODOs

- [x] Fix OOM in CI https://github.com/sigp/lighthouse/pull/7176
- [x] optimise store_hot_state to avoid storing a duplicate state if the summary already exists (should be safe from races now that pruning is cleaner)
- [x] mispelled: get_ancenstor_state_root
- [x] get_ancestor_state_root should use state summaries
- [x] Prevent split from changing during ancestor calc
- [x] Use same hierarchy for hot and cold

### TODO Good optimization for future PRs

- [ ] On the migration, if the latest hot snapshot is aligned with the cold snapshot migrate the diffs instead of the full states.
```
align slot  time
10485760    Nov-26-2024
12582912    Sep-14-2025
14680064    Jul-02-2026
```

### TODO Maybe things good to have

- [ ] Rename anchor_slot https://github.com/sigp/lighthouse/compare/tree-states-hot-rebase-oom...dapplion:lighthouse:tree-states-hot-anchor-slot-rename?expand=1
- [ ] Make anchor fields not public such that they must be mutated through a method. To prevent un-wanted changes of the anchor_slot

### NOTTODO

- [ ] Use fork-choice and a new method [`descendants_of_checkpoint`](ca2388e196 (diff-046fbdb517ca16b80e4464c2c824cf001a74a0a94ac0065e635768ac391062a8)) to filter only the state summaries that descend of finalized checkpoint]

beacon_node/store/src/errors.rs

@@ -1,6 +1,6 @@
 use crate::chunked_vector::ChunkError;
 use crate::config::StoreConfigError;
-use crate::hot_cold_store::HotColdDBError;
+use crate::hot_cold_store::{HotColdDBError, StateSummaryIteratorError};
 use crate::{hdiff, DBColumn};
 #[cfg(feature = "leveldb")]
 use leveldb::error::Error as LevelDBError;
@@ -26,6 +26,9 @@ pub enum Error {
     SplitPointModified(Slot, Slot),
     ConfigError(StoreConfigError),
     MigrationError(String),
+    /// The store's `anchor_info` is still the default uninitialized value when attempting a state
+    /// write
+    AnchorUninitialized,
     /// The store's `anchor_info` was mutated concurrently, the latest modification wasn't applied.
     AnchorInfoConcurrentMutation,
     /// The store's `blob_info` was mutated concurrently, the latest modification wasn't applied.
@@ -47,11 +50,16 @@ pub enum Error {
         expected: Hash256,
         computed: Hash256,
     },
+    MissingState(Hash256),
+    MissingHotStateSummary(Hash256),
+    MissingHotStateSnapshot(Hash256, Slot),
     MissingGenesisState,
     MissingSnapshot(Slot),
+    LoadingHotHdiffBufferError(String, Hash256, Box<Error>),
+    LoadingHotStateError(String, Hash256, Box<Error>),
     BlockReplayError(BlockReplayError),
     AddPayloadLogicError,
-    InvalidKey,
+    InvalidKey(String),
     InvalidBytes,
     InconsistentFork(InconsistentFork),
     #[cfg(feature = "leveldb")]
@@ -75,6 +83,26 @@ pub enum Error {
     MissingBlock(Hash256),
     GenesisStateUnknown,
     ArithError(safe_arith::ArithError),
+    MismatchedDiffBaseState {
+        expected_slot: Slot,
+        stored_slot: Slot,
+    },
+    SnapshotDiffBaseState {
+        slot: Slot,
+    },
+    LoadAnchorInfo(Box<Error>),
+    LoadSplit(Box<Error>),
+    LoadBlobInfo(Box<Error>),
+    LoadDataColumnInfo(Box<Error>),
+    LoadConfig(Box<Error>),
+    LoadHotStateSummary(Hash256, Box<Error>),
+    LoadHotStateSummaryForSplit(Box<Error>),
+    StateSummaryIteratorError {
+        error: StateSummaryIteratorError,
+        from_state_root: Hash256,
+        from_state_slot: Slot,
+        target_slot: Slot,
+    },
 }
 
 pub trait HandleUnavailable<T> {