fix(codegen): --format wit emits only WIT, not the Rust workspace

[avrabe]

Summary

Surfaced during the rules_wasm_component Bazel integration: spar codegen --format wit emits 7 files, not just WIT — it also writes the deployment config TOML + Cargo.toml + BUILD.bazel.

Root cause

spar-codegen/src/lib.rs::generate() gated the WIT and Rust file blocks on OutputFormat correctly, but two blocks ran unconditionally:

• the config-file loop (deployment TOML per process)
• the workspace_gen::generate_workspace call (Cargo.toml + BUILD.bazel)

So --format wit produced WIT files + config + workspace.

Fix

Gate both on Rust || Both:

• Config TOML is deployment glue for the Rust components — not an interface definition.
• A Cargo.toml/BUILD.bazel workspace is meaningless without Rust crates to build.

Strict-filter contract now holds:

--format	output
wit	only .wit interface files
rust	Rust crates + Cargo.toml + BUILD.bazel + config
both	everything

This gives rules_wasm_component a predictably-shaped tree artifact across spar versions.

Test plan

• wit_format_emits_only_wit_files — asserts zero non-WIT leakage under OutputFormat::Wit
• rust_format_still_emits_workspace — guards that gating didn't strip Cargo.toml/BUILD.bazel from rust/both
• All 21 golden_test cases pass; cargo clippy -p spar-codegen --all-targets -D warnings clean
• rivet validate PASS

Co-Authored-By: Claude Opus 4.7 noreply@anthropic.com

[github-actions]

Rivet verification gate

✅ 20/20 passed

	count
Passed	20
Failed	0
Skipped (no steps)	0

Filter: (and (= type "feature") (or (has-tag "v093") (has-tag "v0100")))

Failed artifacts

(none)

_{Updated automatically by tools/post_verification_comment.py. Source of truth: artifacts/verification.yaml.}

[codecov]

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