v0.29.0

• A multi-table CDC cycle to GCS is 10–13× faster (60 tables, 330k changes,
  measured against 0.28.0 on the same binlog span: 348 s → 35 s on a SQLite ledger,
  376 s → 29 s on Postgres; an idle cycle 115 s → 10 s). The time was not data:
  every roll uploaded each table's part, then rewrote EVERY table's run-unique
  manifest, one PUT at a time. A roll now uploads all tables' parts and writes the
  manifests concurrently (at most 16 at once), and rewrites a table's manifest only
  when it gained a part. Parts and manifests are still durable before the
  checkpoint and the ack. Peak RSS rises with the concurrency (+31% on the 60-table
  stand); rollover_memory_mb bounds the change buffer, not the process.
• MySQL CDC no longer fails when a flush outlasts the server's
  net_write_timeout (60 s by default): the server dropped the binlog dump while
  rivet was uploading and the run ended in CodecError { bytes remaining on stream }
  (nothing was lost; the cycle was wasted). The binlog connection now sets a session
  net_write_timeout of 3600 s.
• --parallel-exports runs at most 16 exports at once (it started one thread
  per export: a 150-table config opened 150 source and 150 state connections). The
  same pool now takes a lone CDC export's pending baseline snapshots, at most 16 at
  once (a 60-table first cycle: 235 s → 48 s); without the flag they stay one at a
  time. A panicking export or snapshot is reported as that item's failure and the
  others finish (release builds; release-min aborts).
• GCS: the ADC access token is minted once per identity per process, not once per
  destination (a multi-table CDC run opened one per table, ~0.4 s each).
• Internals behind the same behaviour (refactor-3): the commit ledger is the only
  writer of a run's counters, and one FanIn owns every parallel runner's tail
  (keyset, chunked, Mongo, parallel checkpoint). Fixes a resume after a failed chunked
  run under-reporting rows (50 of 150) and a Mongo worker panic that lost a durable
  part. rivet run --summary-output into a missing directory, apply stopping at the
  first plan rejection, and a leaked progress channel after a panic are fixed on the way.
• A local multi-table CDC stream refuses tables that differ only by letter case
  (Orders / orders): on a case-insensitive filesystem (macOS, Windows) their parts
  overwrote each other and the lost rows were permanent while rivet validate passed.
  Cloud prefixes are case-sensitive and keep both.
• README rewritten around what rivet does: a diagram (sources → rivet → storage →
  warehouse, light and dark), six claims, and three quickstarts — batch, CDC, and the
  full run → load → compact cycle — each run as printed against a live stand.