Add AOF replication for RangeIndex migration

[tiagonapoli]

What

Adds AOF replication for migrated RangeIndex (BF-Tree) keys, so a migrated
index reaches replicas and survives crash recovery with its full data — not just
an empty tree rebuilt from the stub.

Why

When a node receives a migrated RI key, PublishMigratedIndex created the store
record via a RICREATE RMW that auto-logged only the stub to the AOF. On AOF
replay, HandleRangeIndexCreateReplay rebuilds an empty tree from the stub
config, so the migrated data never reached secondaries or survived recovery
(the TODO(RI) at RangeIndexManager.Migration.cs). A BF-Tree file can also
exceed a single AOF page, so it must be chunked.

How

• RISTREAM — a new internal, AOF-only pseudo-command (never parsed from the
  network), intercepted in AofProcessor.StoreRMW alongside
  RICREATE/RISET/RIDEL.
• Primary/publish (ReplicateRangeIndexStream): the reassembled BfTree file is
  streamed into the AOF as chunked RISTREAM entries (reusing
  RangeIndexChunkedSerializer), each entry keyed by the RI key and no larger than
  DefaultMigrationChunkSize; the final chunk is flagged.
• Replay (HandleRangeIndexStreamReplay): a per-key
  RangeIndexChunkedDeserializer reassembles the file across interleaved AOF
  entries (all chunks for one key hash to a single virtual sublog, so they arrive
  in order on one replay task), then publishes via PublishMigratedIndex — which
  re-streams on a chained replica. Incomplete reassembly (crash mid-stream) is
  dropped by CleanupIncompleteStreamReassembly.
• RICREATE suppression: the local RICREATE RMW carries the
  StreamedPublishLogArg sentinel so WriteLogRMW skips its auto-log. The
  RISTREAM stream is the single AOF source of truth for a migrated key; keeping a
  competing empty-tree RICREATE entry would cause data loss on replay in either
  ordering (it would block the publish via the KeyExists gate, or clobber the
  reassembled tree).

Source-side deletion of the migrated key already replicates via the normal
DELETE -> AOF path (out of scope here).

Tests

• ClusterMigrateRangeIndexReplicatesToReplicaViaAof — a migrated DISK-backed RI
  key replicates to the destination primary's replica via AOF; the replica serves
  the full data.
• ClusterMigrateRangeIndexRecoversFromAof — the destination primary reconstructs
  the migrated key from its own AOF on restart.
• Full migrate.rangeindex suite (21) green; RangeIndexChunkedSerializerTests
  (57) and RangeIndexMigrationReceiveStateTests (2) green; full solution builds
  with 0 warnings.

Notes

• MIGRATE REPLACE for RI keys remains unsupported (pre-existing TODO).
• Preview feature (--enable-range-index-preview).

Draft: opening for review; not yet linked to a tracking issue.

[Copilot]

Pull request overview

Adds end-to-end AOF transport for migrated RangeIndex (BF-Tree) keys by streaming the serialized BF-Tree file into the AOF as chunked entries, then reassembling and publishing the full index during replication replay and crash recovery. This closes the “empty tree on replay” gap for migrated range indexes and adds targeted tests to validate both live replica sync and restart recovery paths.

Changes:

• Introduces a new AOF entry type for chunked RangeIndex stream replication and adds replay handling that reassembles/publishes the migrated BF-Tree.
• Suppresses the auto-logged RICREATE stub during migration publish so the stream becomes the single AOF source of truth.
• Expands cluster migration tests (including multi-chunk and interleaving scenarios) and adds unit tests for replay-side reassembly bookkeeping.

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
test/standalone/Garnet.test/RangeIndexStreamReplayTests.cs	Adds unit tests validating replay-side stream reassembly bookkeeping and cleanup behaviors.
test/standalone/Garnet.test/RangeIndexChunkedSerializerTests.cs	Updates RangeIndexMigrationReader construction to match the new parameter naming/API.
test/standalone/Garnet.test/CapturingLogger.cs	Adds a structured-log capturing test logger to assert on structured fields (e.g., reason).
test/cluster/Garnet.test.cluster/ClusterTestContext.cs	Adds a test hook to force small RangeIndex stream chunk sizes across nodes.
test/cluster/Garnet.test.cluster.migrate.rangeindex/ClusterRangeIndexMigrateTests.cs	Adds/extends cluster tests to verify migrated RI replication via AOF and recovery across restarts, including multi-chunk/interleaving/failover.
libs/server/Storage/Functions/MainStore/PrivateMethods.cs	Skips auto-AOF logging for migration-publish RICREATE using a sentinel argument.
libs/server/Resp/RangeIndex/RangeIndexReplicationActivities.cs	Adds structured activity logging for stream replication and reassembly.
libs/server/Resp/RangeIndex/RangeIndexMigrationReader.cs	Refactors reader to accept a general Stream, adds sync chunk read, and introduces a default internal read-buffer size.
libs/server/Resp/RangeIndex/RangeIndexManager.Replication.cs	Implements AOF chunk streaming, replay reassembly state, and publish-on-complete handling for migrated indexes.
libs/server/Resp/RangeIndex/RangeIndexManager.Migration.cs	Publishes migrated indexes by first streaming snapshot into AOF, then suppressing the competing RICREATE AOF entry.
libs/server/Resp/RangeIndex/RangeIndexManager.cs	Ensures incomplete reassembly state is dropped during manager disposal.
libs/server/AOF/AofProcessor.cs	Adds replay dispatch for the new RangeIndex stream chunk entry type and cleanup on dispose.
libs/server/AOF/AofEntryType.cs	Introduces RangeIndexStreamChunk AOF entry type and marks it replayable/store-type.
libs/host/GarnetServer.cs	Adds startup validation that AOF page size can accommodate RangeIndex stream chunks when preview is enabled.
libs/host/Garnet.host.csproj	Adds InternalsVisibleTo for cluster tests.
libs/cluster/Session/RangeIndexMigrationReceiveSession.cs	Passes AOF handle into migrated-index publish so the target primary can stream to its replicas via AOF.
libs/cluster/Session/ClusterSession.cs	Wires append-only file into the RangeIndex migration receive state.
libs/cluster/Server/Migration/RangeIndex/RangeIndexMigrationActivities.cs	Minor doc comment formatting change in migration activity tracing.
libs/cluster/Server/Migration/MigrateSession.RangeIndex.cs	Updates migration transmit to use the updated snapshot+reader API.