Syncular 0.26.6

0.26.6 is a patch release for the TypeScript server's error handling
(SYNCULAR-ERROR-CLASS-001) and for serving SQLite images from hosts without a
SQLite engine. SSP2 stays at wire version 3. The error catalog gains one code,
the Rust core changes its retry scheduling, and every package and crate ships
together.

• Unexpected exceptions answer sync.internal_error. An adapter answered
  any exception that was not a SyncError with HTTP 400
  sync.invalid_request and the exception text as the message, so clients
  stopped retrying a transient fault, internal messages reached clients, and
  hosts saw nothing. The new §10.2 code sync.internal_error (category
  internal, retryable, retryLater, HTTP 500) answers every such case in
  createSyncularHono (sync, operations, segments, blobs, and throws from
  authenticate), createSyncularAdminRoutes, the Workers Durable Object's
  HTTP sync and connect paths, and a realtime socket round (in-band, before
  the first response byte; a mid-stream failure still drops the connection).
  The message is fixed and never carries the exception text.
• onError receives the original exception. SyncServerConfig.onError
  (and SyncularAdminRoutesOptions.onError) receives (error, { route })
  for each of those cases and for remote operations that fail unexpectedly,
  which keep their operation.* code. A throwing handler does not change the
  response.
• The Rust core retries catalog-retryable server codes. It scheduled a
  background retry only after transport failures; a server answer carrying
  sync.internal_error, sync.rate_limited, sync.schema_not_ready, or
  another code §10.2 marks retryable now schedules one, as the TypeScript core
  does. The conformance scenario errors/internal-error-retryable pins both
  cores.
• Sqlite-lane bootstraps pin at their scope. A bootstrap eligible for the
  §5.3 image lane pins at the newest commit that changed a row in its scope,
  capped at maxCommitSeq and raised to the horizon (§4.7), where it pinned
  at maxCommitSeq. A stored image therefore stays the match for its reuse
  key across commits to other tables or scopes. The next incremental pull
  replays the empty window from the pin. The pin, the image lookup, and the
  eligibility probe of every such subscription are read before the first
  frame, batched per table like the rest of the pull.
• publishSqliteImage stores images offline. It runs the pull's bootstrap
  path for one table and scope set with a sqliteImageBuilder, so a Bun
  process with the production storage stores the image a Workers host finds.
  writeSqliteImage is exported for custom builders. An image lives for the
  segment store's ttlMs at publication.
• Large segments stream. SegmentStore.open (optional; implemented by
  S3SegmentStore and MemorySegmentStore) returns the record and a byte
  stream. openSegmentDownload authorizes like handleSegmentDownload and
  returns the stream, and the Hono segments route relays a segment above
  16 MiB without buffering it, gzip-encoded when accepted.

Upgrade note. ServerStorage gains the required
latestScopedChangeSeq(partition, { table, scopeFilter }); the three in-tree
storages implement it, and a custom storage must add it (an index-only
max(commit_seq) over sync_change_scopes per first-variable value).
Treat HTTP 500 sync.internal_error as retryable in custom clients.