chore: upgrade Swift binding to 1.16.0

[zxch3n]

Summary

• bump loro-swift from 1.13.3 to 1.16.0
• upgrade loro-ffi from 1.13.7 to 1.16.0
• refresh Cargo.lock against the published crates (loro, loro-common, loro-internal, loro-kv-store 1.13.x -> 1.16.0)

Upstream loro-ffi v1.13.7..v1.16.0 only touches Cargo.toml/Cargo.lock (loro 1.13.7 -> 1.16.0); src/ is unchanged, so the UniFFI interface and the generated Swift bindings are unchanged.

This brings the Swift binding up to the loro 1.16 line (1.14 richtext/import fixes, 1.15 UndoManager pause/resume + styled-text fixes, 1.16 bulk deep-read APIs and shallow-snapshot/memory fixes).

Verification

• RUSTUP_TOOLCHAIN=1.87.0 sh scripts/build_macos.sh (same toolchain as CI)
• LOCAL_BUILD=true swift test -> 42 tests, 0 failures
• regenerated Sources/Loro/LoroFFI.swift is byte-identical (no diff in Sources/)