dendro v0.1.0

First release. The crate is a segmented Parquet archive with a write-ahead
log, in a single SQLite file: rows land in the WAL and are periodically sealed
into immutable parquet segments, with the catalog, retention, crash recovery
and rewriting around them. A row is a timestamp, a wall-clock offset and opaque bytes; what the
bytes mean is the caller's, expressed through one trait.

Added

• Writer, source, stream, segment and row model, with the WAL readable rather
  than a staging area, and snapshot isolation for readers.
• SegmentEncoder, the whole schema boundary, plus an encoder version marker
  that refuses a reader whose encoder disagrees with the writer's.
• Per-stream retention by time, with the size accounting a cap needs.
• Reopening an archive and resuming a source, with writer sessions recorded
  and a floor that refuses an append behind where the previous session stopped.
• Out-of-order appends are dropped rather than silently stored, counted per
  source and logged once per stream.
• The caller's time-keyed store, caller_rows: opaque rows against
  (source, stream, ts) that the archive reads by range, evicts by the same
  cutoff as segments, carries verbatim in every copy, and never decodes or
  merges. Transaction::insert_caller_rows, ArchiveMut::insert_caller_rows,
  SourceWriter::caller_rows, Archive::read_caller_rows and
  Archive::caller_row_streams; Evicted::caller_rows counts what
  retention removed. A store row does not make a stream exist. This is the
  store the schema-churn journal entry owed to a caller that keeps column
  identity in a secondary index.
• An opaque per-segment index slot, so a caller that builds its own index over
  segment contents can keep it in the archive and stay one file.
• Archive::verify, reporting every problem it finds in one pass.
• read::describe, one call for the whole catalog plus the file's own size.
• Optional wall-clock alignment for segment boundaries.
• rewrite::compact, merging a stream's small segments and reclaiming the
  space, measured at 18.2x read and 2.38x size between 400 segments and one.
• SchemaPolicy::UnionFields, opting into merging across a column set that
  grew or shrank.
• Rewriting: combine, trim, range-copy and opt-in column projection.
• An archive is exactly a file that carries dendro's header stamp. There is
  no fallback to a catalog table and no legacy schema: a .rez recording
  from before dendro is upgraded by rezolus, which still reads it.
• archive::ArchiveMut, the write handle, beside Archive, which now only reads.
  Archive::open is read-only (the former open_read_only), works on read-only
  media and on a file another process is writing, and is the only open the
  read paths use. ArchiveMut::create makes a new archive; ArchiveMut::open takes an
  existing one with SQLite's exclusive locking mode, so it is refused as
  Error::InUse while anything else holds the file, and it refuses read-only
  media by name. ArchiveMut derefs to Archive. Before this, a
  second read-write connection on a file the writer thread held wrote
  silently and left the writer's cached sequence numbers and watermarks
  wrong. Seven crate-internal methods (open_for_write, remove_archive,
  next_seqs, source_time_span, total_wal_rows, the pragma readers) left
  the public surface, and ReadOnly::Handle is gone because a read handle
  has nothing to refuse.
• Each writer_sessions entry records the dendro crate version that
  appended, under dendro. Provenance for tracing a defect to the sessions
  that had it, never a gate: readability is the header's schema version.
• keys::PRODUCER_VERSION, a reserved metadata key for the version of the
  software that produced a source's values. Written by the producer, stored
  opaquely, never parsed. Distinct from encoder, which versions the row
  encoding and which dendro enforces: a producer that keeps its encoding and
  changes what it measures moves every value while the encoder version stays
  identical, which is the case encoder cannot see.
  (rezolus #1195.)

Notes

• Minimum supported Rust version is 1.85, the floor the dependency graph
  sets. Raising it is a minor-version change and is gated in CI.
• The reader configuration (--no-default-features) drops the writer thread
  and is what builds for wasm32-unknown-unknown. It is a supported
  configuration, tested in CI.