v0.1.0: canonical log

The first release: the canonical log, the chain tracker and the consumer runtime. evmsync needs
Go 1.26 or later.

Added

• chain: the block, header and log values, BlockRef with its parent hash, the ingest Filter
  (up to 1,000 addresses and 1,000 values in each of four topic positions) with a bloom check,
  and the Source interface that ingest reads a chain through.
• chainlog: the Block, Revert and Finalize entries and their binary record format, limited
  to 16 MiB per record. Every append goes through a validator State: a block extends the tip, a
  revert targets the finalized block or a block in the window, and a finalize never moves below
  the finalized block.
• chainlog.Memory: an in-memory log that passes the same conformance suite as the WAL.
• chainlog/wal: a durable log in segment files with CRC-32C checksums, on Unix systems. It takes
  an exclusive lock on its directory, recovers a torn tail on open, keeps a checkpoint and a meta
  file, fsyncs per SyncPolicy, and compacts whole segments below the finalized block.
• tracker: turns new heads and finalized blocks into log entries. It follows parent hashes to the
  common ancestor of a reorg, caps the window of unfinalized blocks (100,000 by default), and stops
  with a typed error on a reorg below the finalized block or a full window.
• consumer: Run feeds a consumer the log from its committed offset plus one, and Memory keeps
  in-memory state with a snapshot at the latest Finalize that it replays on a Revert.