fix(opy): complete project preprocessing state

[e54-bot]

Summary

• extract settings blocks from included sources while preserving file provenance and lexer positions;
• suppress repeated include imports while retaining directive records, and accept zero-argument function-like defines;
• update issue-142 tests, support documentation, and full-corpus evidence.

Validation

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

The full 63-fixture corpus has no regressions. The affected real-world projects now advance past the #142 project/preprocessing boundaries; remaining failures are later parser or external generator-script boundaries.

Refs #142

[Teakowa]

Major — crates/opy-rs/src/preprocess.rs (imported_files)

Duplicate suppression is keyed by the canonicalized identity. Pinned OverPy 9.7.10 keys imported files by the resolved path string, so aliases such as shared.opy and dir/../shared.opy are distinct imports upstream but collapse here. That can drop the second import's declarations/rules and violates #142's include semantics. Use the reference-visible resolved path identity for duplicate suppression; keep canonical identity separately for cycle detection if needed, and cover an alias-path case.

Major — crates/opy-rs/src/preprocess.rs (duplicate-import early return)

Pinned OverPy emits w_already_imported when a duplicate is suppressed, and the pinned OW1 Emulator oracle records that diagnostic. This implementation silently returns after recording the directive, so the newly declared source-supported behavior loses an observable preprocessing diagnostic. Preserve the duplicate-import warning through the frontend diagnostic contract.

[Teakowa]

Major — crates/opy-rs/src/compiler/mod.rs (compile_source_report_with_locale)

When frontend succeeds with w_already_imported but lowering/integration later fails, the Err(error) branch replaces frontend_diagnostics with only the integration error. The duplicate-import warning is therefore still lost from compile reports on this valid path. Preserve frontend_diagnostics and append the integration diagnostic before returning the failure report.

[Teakowa]

LGTM