Infer Option::None from compound-literal expected types (v0.1.21)

[Cod-e-Codes]

Summary

• Type checker / Codegen: array, tuple, and [value; N] elements, assignment, returned compounds, and enum variant payloads now check against the adjacent expected type (same expr_expected helper as struct fields, call arguments, send, and Box::new). This impacts let a: [Option<int>; 1] = [Option::None], (Option::None, 1), [Option::Some(4)] (emits Option_int, not bare (Option)), x = Option::None, return [Option::None], and Result::Err(Option::None) as a compound element. Unannotated let empty = Option::None still requires an annotation.
• Harness: filtered test_runner.sh skips non-matching TSV rows without a tr process per field. A .ion filter is exact; a bare stem stays a substring.

Test plan

• cargo fmt --check
• cargo test
• cargo clippy -- -D warnings
• tests/test_runner.sh (332 passed locally; Linux CI)
• Example ion-build projects compile (including examples/data_lib)
• Confirm annotated compound Option::None / Option::Some cases compile and run; unannotated let empty = Option::None still errors
• Filtered harness ./test_runner.sh test_tuple_option_none.ion test_option_none_call_arg.ion finishes in seconds and does not pull in test_option_none_call_arg_middle