SQL Anywhere 0.3.1 — CRDT offline merge

SQL Anywhere 0.3.1 — experimental CRDT offline merge

This release packages the CRDT offline-merge work: conflict-free, multi-writer
offline sync via the vendored cr-sqlite extension — the other half of a
local-first stack alongside embedded replicas. Additive and opt-in.

Added

• CRDT offline merge (experimental). Turn tables into conflict-free
  replicated relations with crsql_as_crr(...). Databases can be edited offline
  and merged deterministically by exchanging crsql_changes rows — verified end
  to end (two nodes converge; concurrent same-row edits resolve the same way on
  both sides).
• Prebuilt extensions attached below for macOS Apple Silicon and Ubuntu
  Intel/ARM (crsqlite-v0.3.1-<target>.tar.gz). Or build it yourself with
  scripts/build-crsqlite.sh.
• Rust API support — sqlanywhere/examples/crdt_sync.rs drives the whole
  merge through the sqlanywhere client; sqlanywhere/tests/crdt.rs asserts it
  in CI against a freshly built extension.

Docs

• Guide (why / how / examples): docs/CRDT.md
• Full changelog: https://github.com/kwhorne/sql-anywhere/blob/main/CHANGELOG.md

Notes

Not yet bundled inside sqld (load it as an extension). Static linking is
tracked on the roadmap.