CLI: add doctor checks for fixture availability

[Timi16]

Overview

Many commands depend on fixture WASM files, but doctor does not report missing or stale fixtures.

Background

Diagnostics is already present in the repository, but the current implementation leaves a concrete gap for users or maintainers. Relevant files: src/cli/commands.rs, tests/fixtures/manifest.json.

Specifications

• Read tests/fixtures/manifest.json when present.
• Report missing fixture files and hash mismatches.
• Keep normal doctor runs fast.
• Include JSON fields for fixture status.

Acceptance Criteria

• Behavior is covered by focused tests or documented manual verification.
• Errors are handled gracefully with actionable suggestions.
• Help text or docs are updated when the user-facing behavior changes.

[mich-sys]

@mich-sys has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

hi team,
kindly assign this to me

ℹ️ Repo Maintainers: To accept this application, review their application or assign @mich-sys to this issue.

[championdor2026]

@championdor2026 has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Good Day, Maintainer.

I'm a well-experienced developer. I want to take up this issue and solve it diligently. Please grant my request....Thank you.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @championdor2026 to this issue.

[Tomi-whizzy]

@Tomi-whizzy has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

I would love to work on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Tomi-whizzy to this issue.

[drips-wave]

Congratulations, @Tomi-whizzy! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

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