fix: WASM crash in cloudsync_set_column on tables with existing rows

[andinux]

Summary

Calling cloudsync_set_column(table, col, 'algo', 'block') on a table with pre-existing rows crashes the WASM build with RuntimeError: function signature mismatch as soon as the block-index
migration tries to allocate memory. Native builds are unaffected.

Root cause

src/block.c:137 cast cloudsync_memory_alloc directly into the fractional-indexing allocator slot:

.malloc = (void ()(size_t))cloudsync_memory_alloc,

• cloudsync_memory_alloc → dbmem_alloc(uint64_t)
• fractional_indexing_allocator.malloc is void ()(size_t)

On native platforms size_t is 64-bit, so the cast is a no-op. In WASM size_t is 32-bit, and call_indirect enforces strict type checking: the function is registered in the table as (i64) -> i32 but
called as (i32) -> i32 — immediate runtime error. Documented Emscripten pitfall: https://emscripten.org/docs/porting/guidelines/function_pointer_issues.html

Fix

Bridge through a thin fi_malloc_wrapper, mirroring the existing fi_calloc_wrapper pattern already used for the calloc slot. free is already fine (dbmem_free(void*) matches the expected signature
on every target).

Changes

• src/block.c — new fi_malloc_wrapper, used in block_init_allocator
• src/cloudsync.h — CLOUDSYNC_VERSION → 1.0.16
• CHANGELOG.md — 1.0.16 entry

Test plan

• make clean && make && make unittest — all tests pass (Block LWW suite + Memory Leaks Check)
• make postgres-docker-run-test — 0 failures
• Verify in a WASM build: cloudsync_set_column on a table with existing rows no longer raises function signature mismatch
• Smoke-test block-level LWW roundtrip in the WASM environment