test(aidd-fix): add unit tests for /aidd-fix skill prompts

[ianwhitedeveloper]

The /aidd-fix skill introduced in #103 has no unit tests. Unit testing is intentionally deferred until the riteway AI Testing Framework lands, which provides the infrastructure for treating prompts as first-class testable units.

Acceptance Criteria

• Unit tests are written for the /aidd-fix skill prompts using the riteway AI testing framework
• Tests cover the core workflow steps (context validation, epic documentation, TDD, implement, review, commit)
• Tests are colocated with the skill (ai/skills/aidd-fix/)

Blocked by

• feat(ai): AI Testing Framework — consolidation staging branch [8/8 → master] riteway#411 — AI Testing Framework must merge before this can be implemented

[ianwhitedeveloper]

Blocked until feature release for riteway#411 has been published to npm