[PierreRaybaut]

Summary

Follow-up of the updated review of the develop branches (R1, remainder of A02).

FileSystemSyncAccessHandle.read()/write() return the number of bytes actually transferred, which the File System standard allows to be lower than requested. OpfsSyncObjectStore ignored it:

• a short write was truncated/extended to the payload length and reported as stored: the runtime released the object from memory while its file held partial data;
• a short read returned a buffer partly filled with zeros, without error.

put() now writes the remaining bytes in turn and throws when a write transfers nothing, before recording the size: the existing spill rollback (persistOrRestore) then keeps the object resident. get() reads in turn and throws when the file cannot be read up to its size.

Tests

• Store: payload written and read in several fragments; write making no progress; write failing after a first fragment; read unable to reach the end of the file (4 tests fail without the fix).
• Runtime: an incomplete write rolls the object back to memory, like a quota error.
• Vitest 897 passed (107 files), lint, format, i18n check, production build.