SW-220 — Add a malformed package-script metadata matrix for the dev resolver #402

Summary

The dev resolver validates the package scripts object and selected script values, but its tests do not comprehensively pin behavior for null, array, primitive, and non-string script metadata. Add a focused dev-only malformed-manifest matrix so invalid metadata cannot reach npm. This issue does not cover test project detection or Node/Cargo ambiguity, which remain in #119.

Workstream

• Workstream: WS-DEV
• Primary scope: src/dev/project.ts; tests/dev-project.test.ts
• Priority: P2
• Difficulty: low
• Proposed points: 100
• Protected surface: No

Acceptance Criteria

• Null, array, and primitive scripts values are rejected.
• Non-string selected dev/start/start:backend script values are rejected or skipped according to a documented precedence rule.
• Error categories are actionable and consistent.
• Invalid metadata is rejected before process-plan creation or npm spawn.
• Valid dev scripts continue to resolve unchanged.
• Tests explicitly distinguish malformed scripts metadata from missing or blank script values.

Dependencies

• SW-212

Out of Scope

• Test resolver and Node/Cargo ambiguity covered by SW-066 — Expand unsupported-project detection fixtures for stellarforge test #119.
• Adding new script names or changing npm invocation behavior.
• New runtime dependencies.

Definition of Done

• Deterministic regression tests cover each malformed scripts shape.
• Supported-platform CI passes.

Labels

• Stellar Wave (do not apply until activation is explicitly authorized)
• type: test
• area: dev
• priority: P2
• difficulty: low
• points: 100
• workstream: dev