Add advisory for sized-chunks: panic-safety UAF/double-free in clear/drop_left/drop_right

crates/sized-chunks/RUSTSEC-0000-0000.md

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+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "sized-chunks"
+date = "2026-08-04"
+categories = ["memory-corruption"]
+keywords = ["panic-safety", "memory-safety", "use-after-free", "double-free"]
+informational = "unsound"
+
+[versions]
+patched = []
+unaffected = []
+```
+
+# Panic-safety unsoundness in `Chunk`, `RingBuffer`, and `InlineArray` (use-after-free / double-free)
+
+Several methods in `sized-chunks` drop elements before updating the container's
+length/boundary metadata. If an element's `Drop` panics during the drop, the metadata
+update is skipped, so the container still treats the already-dropped elements as live.
+When the container is later dropped, its own `Drop` re-visits those slots and drops the
+freed elements again — a use-after-free / double-free reachable from safe Rust.
+
+## Affected methods
+
+- `InlineArray::clear`
+- `Chunk::clear`, `Chunk::drop_left`, `Chunk::drop_right`
+- `RingBuffer::clear`, `RingBuffer::drop_left`, `RingBuffer::drop_right`
+  (require the `ringbuffer` feature)
+
+## Impact
+
+- **CWE-415 (Double Free):** the same allocation is freed twice (e.g. an element holding `Box<T>`).
+- **CWE-416 (Use-After-Free):** an element reads its own freed allocation during `Drop` (e.g. `String`) — confirmed under AddressSanitizer.
+
+All seven are reachable entirely from safe Rust via `catch_unwind` with element types
+whose `Drop` can panic.
+
+## Status
+
+The repository is archived and unmaintained (no release in several years), so no upstream
+fix is expected. Affected users should avoid these methods with element types whose `Drop`
+can panic, or migrate away from the crate.