test(settings): pin parse/check/emit agreement on members and blocks

[e54-bot]

Summary

Adds a standalone check_emit_agreement test target (new [[test]] in crates/workshop-rs/Cargo.toml + tests/check_emit_agreement.rs, 10 tests) that runs parsed sources and producer-built Settings trees through parse → check → emit and asserts the accept/reject verdict is identical at every reachable stage, per #459.

Covered areas:

• Hero settings members (fix(settings): reject hero settings members for slots the hero lacks #438 shape): slot-less members under a row-less hero (doctrine + enableAbility3/ability3Cooldown%/enablePassive) are rejected by check with the missing-slot diagnostic and fail emission with the missing-mapping error; the accepted counterparts (gameplay-name resolution, reviewed label rows, shared labels, carried raw members) pass both stages.
• Catalogued vs uncatalogued keyed blocks (feat(settings): carry blocks under catalogued keys as written #413/feat(settings): emit pass-through member blocks verbatim at resolved positions #424 shapes): 9 position pairs (lobby, main, extensions, catalogued/uncatalogued modes, hero, team, top level, workshop) asserting identical verdicts for key { ... } blocks whether or not the key is declared; both stages reject the team-position cases (unknown hero).
• Producer-only shapes: RawGroup pass-through at team/mode/top-level/hero positions vs resolved Group at the same positions, typed leaves inside carried blocks, misplaced Workshop/leaf nodes, kind mismatches — all asserted to agree.
• Carried near-miss members warn (severity=Warning) while both stages accept; accepted sources emit text that reparses and re-passes check.

Disagreements found: none — the covered surface is currently consistent, so no source fix was needed.

Sensitivity proof (both directions, run before commit):

• Dropping the unemittable_hero_member guard (src/settings/check.rs walk_heroes) → check accepts doctrine/enableAbility3 while emit still fails with missing setting mapping → 2 tests fail.
• Reverting the carried-block arm to (Group\|RawGroup, None) in check_member → check rejects lobby/Map Rotation { } (does not match its table kind) while emit accepts → 4 tests fail.
• Guard restored; suite green again.

Test plan

• cargo test -p workshop-rs --test check_emit_agreement → 10 passed
• cargo test -p workshop-rs --lib → 314 passed (settings_pipeline, audit_regressions, emitter, parser all green)
• cargo test -p workshop-rs --test integration → 199 passed
• cargo fmt --all -- --check → clean; cargo clippy --workspace --all-targets -- -D warnings → clean; git diff --check → clean

Fixes #459

[Teakowa]

Reviewed line by line and verified locally: the new tests run green against the PR code, coverage matches the issue's acceptance criteria, and the documented sensitivity proofs hold.