Support delete mode ('d') for in-memory zip streams (#333)

[kuba--]

Allow zip_stream_open to accept 'd' mode so callers can delete entries from an in-memory archive without duplicating the buffer. A dedicated write function (zip_stream_delete_write_func) keeps the same heap-write semantics as miniz but uses a distinct pointer so mz_zip_writer_end won't free the caller's buffer—no miniz changes required.

Seven new ASan-clean tests cover delete-by-name, delete-by-index, invalid indices, close-without-copy, open-then-close, delete-all, and multiple zip_stream_copy calls.

[Copilot]

Pull request overview

Adds support for opening in-memory ZIP archives in delete mode ('d') so callers can remove entries from a memory-backed archive and then obtain the modified archive via zip_stream_copy(), without requiring miniz changes.

Changes:

• Add a dedicated in-memory write callback for delete mode to avoid miniz freeing the caller’s buffer on close.
• Extend zip_stream_openwitherror() to accept 'd' mode for memory streams.
• Add a suite of stream-delete tests (delete by name/index, invalid indices, open/close cases, delete-all, multi-copy).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
test/test_entry.c	Adds new test coverage for stream-based delete mode workflows.
src/zip.h	Documents new 'd' mode for zip_stream_open*() APIs.
src/zip.c	Implements 'd' mode for stream open and a custom write function to preserve caller buffer ownership.

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[Copilot]

@kuba-- I've opened a new pull request, #392, to work on those changes. Once the pull request is ready, I'll request review from you.