Fix marshal recursive reference loading - #8501

• This PR follows our AI policy

Summary

Create reference-tracked containers before unmarshalling their children, matching CPython's r_object() construction order. This restores recursive list and dict graphs as well as indirect tuple cycles.

The compiler-core decoder exposes optional placeholder/fill hooks, while the VM bag supplies RustPython object construction. Tuple storage gains an initialization-only mutation path corresponding to PyTuple_New followed by PyTuple_SET_ITEM; tuples remain immutable after decoding. Interned marshal string markers are also preserved through the runtime bag.

Python exceptions raised while inserting unmarshaled set and dictionary members are retained in a call-local pending-error slot. Abnormal self-referential hash containers therefore raise TypeError like CPython instead of being collapsed into a generic ValueError; immutable reference loops continue to raise ValueError. This also removes the remaining test_loads_abnormal_reference_loops expected failure and replaces insertion-path unwrap() calls with ordinary error propagation.

AI assistance disclosure: Codex (gpt-5) assisted with implementation, test execution, and drafting this pull request. The changes were exercised with the RustPython interpreter and full project test commands listed below.

Testing

• cargo fmt --check
• prek run --all-files
• cargo run --release -- -m test test_marshal
• Direct CPython 3.14-compatible exception checks for malformed recursive dict, set, slice, and frozenset streams
• cargo test -p rustpython-compiler-core -p rustpython-vm
• cargo clippy -p rustpython-compiler-core -p rustpython-vm --all-targets
• cargo test --workspace --exclude rustpython_wasm --exclude rustpython-venvlauncher --exclude rustpython-capi
• (cd crates/capi && cargo test)
• Consumed the patched compiler-core from Pyre via a workspace-wide Cargo source override and ran cargo check --offline -p pyre-interpreter --features dynasm.