feat(opy): complete semantic HIR subroutine resolution

[e54-bot]

Summary

• Materialize implicit subroutine declarations for def definitions with source spans.
• Enforce source-order visibility for declarations, definitions, variables, macros, and enums.
• Add stable duplicate diagnostics and tooling regressions for HIR symbols and provenance.
• Update the compiler expectation for the now-successful def-containing corpus fixture while retaining its separate lowering known gap.

Verification

• cargo fmt --all -- --check
• cargo clippy --workspace --all-targets --all-features -- -D warnings
• cargo test --workspace --all-targets --all-features
• python3 compatibility/run_native.py --binary target/debug/opy-cli --semantic-binary target/debug/opy-compat

Fixes #143

[Teakowa]

Major — crates/opy-rs/src/lower.rs: current_order is derived from separate program.declarations / program.rules vector indexes, but the parser allows those top-level forms to interleave in source. This makes every declaration appear before every rule/def, so e.g. a rule can incorrectly see a variable/macro/enum declared later, while a macro can incorrectly fail to see a def written earlier. Preserve one top-level source order (or compare source positions) when enforcing visibility.

Minor — crates/opy-rs/src/lower.rs: duplicate global/player/subroutine declarations use HashMap::insert, which replaces the first declaration's order with the duplicate's order. References between the first and duplicate declarations can then produce spurious unknown-identifier/visibility failures in addition to the duplicate diagnostic. Keep the first binding/order when reporting a duplicate.

[Teakowa]

LGTM